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An abbreviation of "alternating current."

AC Input Power Supply

Acceleration Sensor

A sensor that detects acceleration through changes in rotational movement or motion velocity. Piezoelectric elements as well as semiconductors are used. The motion sensors in smartphones and other devices use MEMS acceleration sensors that utilize MEMS crafting techniques.

Acoustic Filter


A general term for a component that converts a certain energy into mechanical power. Indicates an electric actuator that acquires mechanical motion such as reciprocating motion or lock release from electrical energy, in the field of electrical/electronic equipment. Also called a "plunger", especially in the case of one that acquires reciprocating motion. The actuator incorporating a neodymium magnet has strong magnetic energy despite its small size. Its coil and spring use a micro current providing excellent high-speed response, and it is used in the disk drive locks of a personal computer or a DVD recorder.

ADAS (Advanced Driver Assistance System)

A system that automatically detects pedestrians, vehicles, obstacles, and so on to support vehicle driving operations.

Ag-stacked Film

A functional film with a thin Ag alloy film uniformly formed on a plastic film substrate. Provided by TDK under the product name FleClear®.

AI (Artificial Intelligence)

The realization of intelligent functions equivalent to those of a human including judgment, inference, speech recognition, image recognition, and problem-solving by a computer.

AI Speaker


A calculating technique or processing procedure for solving problems or achieving an objective. Writing an algorithm processed by a computer in a specific language is called programming.

All Solid-State Battery

A lithium ion battery that uses a solid electrolyte in place of a liquid electrolyte. They are characterized by a high level of safety, as there are no concerns about liquid leaks or ignition. TDK has developed an all solid-state battery named CeraCharge® and is selling them.

Alternating Current (AC)

A current in which current flow reverses periodically, the same as in commercial AC power supply. A pulse current is also an alternating current, in a broad sense.


An amorphous state that becomes a solid state lacking distinct crystalline structure. Glass is a typical amorphous substance.

Amorphous Core

A core (magnetic core) made with a thin belt (ribbon) of amorphous alloy manufactured by melting and rapid-cooling iron group elements, such as iron, nickel, and cobalt, and small amounts of additional elements. High permeability and excellent in abrasion resistance. Used in special transformer cores, etc.

Amorphous Silicon Solar Cell

A solar battery using an amorphous silicon semiconductor combining hydrogen with amorphous silicon. Although its energy conversion efficiency is inferior to single crystal silicon or polycrystalline silicon, it is used for solar calculators and solar wrist watches because of its high sensitivity to the wavelength of fluorescent light. Thin and flexible, it features excellent processability to any forms.

Anechoic Chamber

A space where external electromagnetic waves are blocked and the interior is also electromagnetically stabilized. Used to measure noise emitted from electronic devices, examine immunity (resistance to external electromagnetic waves) of electronic devices, and so on. Although noise emitted from electronic devices is basically measured in the open air, since anechoic chamber is not influenced by radio waves from wireless communication equipment, surrounding electromagnetic noise and weather conditions, etc., the demand for anechoic chamber has been increasing more than ever. Anechoic chamber consists of a metal shield structure to block external electromagnetic force, a radio wave absorber to be installed in the surface of a wall or a ceiling to absorb radio waves emitted in the anechoic chamber, and equipment to implement tests, etc.

Angle Sensor

A sensor that detects angle, inclination, and so on in conjunction with rotation. In addition to optical encoders, there are various types such as those that use Hall elements and magnetic sensors (such as TMR sensors).

Angular Velocity Sensor

Anisotropic Magnet/Isotropic Magnet

The crystal grains of magnetic material have a direction in which they are easily magnetized (the axis of easily magnetization). The crystal grains are molded with the axes of easy magnetization not aligned, the material becomes an isotropic magnet, which can be magnetized in the same manner from any direction. In contrast to this, if the material is molded in a magnetic field, the crystal grains are easily magnetized and the axes are aligned, resulting in an anisotropic magnet, which can be strongly magnetized only in a specific direction. Most strong magnets are manufactured as anisotropic magnets.

Antenna Switch

An element that switches transmission and reception through timesharing in wireless communications devices such as smartphones.

Antenna Switch Module

Integrates the antenna switching device and the peripheral high-frequency components of a wireless communication devices like a smartphone. One integrating an antenna switching part and a front end part is known as a Front End Module.


An assembly of several single-components attaining small-size/light-weight/space-saving and low cost, including a capacitor array, a chip bead array, a three-terminal filter array, and a common mode filter array, etc.

Arrestor/Surge Arrestor

A device that protects electronic equipment and facilities from overvoltage or overcurrent such as that caused by a lightning surge. Also referred to as a gas arrestor, as it uses an arc discharge in an enclosed gas.

AR/VR (Augmented Reality/Virtual Reality)

The superimposition of virtual reality (VR) on the real world using a head-mounted display (HMD) or similar device is called augmented reality (AR). Also referred to as mixed reality (MR) and cross reality (XR).

ASIC (Application Specific Integrated Circuit)

A type of IC that combines all necessary functions into a single unit for a specific purpose. Also called custom IC.


A specification to connect an HDD (hard disk drive) and a personal computer. Serial ATA (SATA) is a specification of the serial transmission system attaining a faster transmission speed.

Axial Lead/Radial Lead

Electronic parts include the types that have a lead (terminal) for wiring and the SMD type that does not have lead corresponding to a surface mounting. Leads can be classified into two types: one with two leads on both right and left sides (in the direction of the central axis) of an electronic component is called an "axial lead", and one that has two parallel leads is called a "radial lead."



An impedance-matching element. Balun is a coined term that combines balance and unbalance. An element that combines two circuits with different impedances to facilitate signal feed. It has a similar function to a transformer, but it does not need things like magnetic core due to its high frequency. Things such as a combination of two coreless coils (resonator) is used instead.

Band Pass Filter (BPF)

Bare Die/Bare Chip

A bare silicon chip before connection to a circuit board by wire bonding or other method.

Barometric Pressure Sensor

A sensor that detects air pressure such as the pressure of the atmosphere as well as the intake and exhaust pressure of an automobile. Also used as an altimeter and for other applications. MEMS barometric pressure sensors that use MEMS technology and other types are available.

BAW (Bulk Acoustic Wave) Filter

A high-frequency filter that uses the resonance of bulk acoustic waves (BAW) in a dielectric ceramic thin film.


BGA (Ball Grid Array)

A packaging technology that bonds components to a circuit board by arranging balls of solder on the bottom surface of IC chips in place of lead wires.

B-H Curve

A magnetic hysteresis loops. A curve that expresses the magnetization of a magnetic material when placing the magnetic material such as iron and ferrite into a coil and changing the magnetic field to apply, in a graph. An S-shaped and closed curve with a perpendicular axis as a flux density (B) and a horizontal axis as a magnetic field strength (H). Hard magnetic materials such as hard ferrite used as a permanent magnet have a thick S-shaped curve with wide width, and soft magnetic materials such as a soft ferrite have a thin S-shaped curve with narrow width.

BHmax (Maximum Energy Product)

An index showing potential magnetism strength of a permanent magnet material. The second quadrant of the B-H curve (magnetic history curve) of a ferromagnetic material is called a demagnetization curve. The magnetic energy of a permanent magnet is equivalent to the area of the quadrangle having its vertex in the perpendicular axis/horizontal axis of a graph and one point of a demagnetization curve, and the maximum is called a BHmax (maximum energy product). The S-shaped B-H curve becomes larger and a more thickset square shape with a larger BHmax and a more powerful magnet.


A term that generally means partiality. In an electronic circuit, it means applying a fixed voltage or current to an input in advance.

Bidirectional DC-DC Converter

A power supply that combines a step-down converter and a step-up converter. Used for charging and discharging storage batteries, using energy recovered from a motor, and other applications


A bonding material to be mixed with powder materials in manufacturing of ferrite products, multilayer chip components, etc. After being multi-layered and cut, it is thermally decomposed before firing. This is called a de-binder process.


A short-range wireless communication standard used to wirelessly connect digital devices such as PCs, peripheral devices, and smartphones. Distinguished from wireless LANs, which are used to connect to the Internet.

BMS (Battery Management System)

A protection circuit or module for preventing overcharging, over discharging, excess heat, and so on in a secondary battery such as a lithium ion battery with multiple connected cells.

Bond Magnet

A magnet made by mixing and molding powders of neodymium or ferrite magnets into materials such as plastic and rubber.

Build-Up Method

A method of producing multilayer circuit boards. A method of creating small holes (vias) using laser light and connecting the layers one-by-one to create multiple layers. Higher density wiring is possible compared to conventional multi-layer boards.

Bulk Packaging System

In order to mount chip components on a circuit board surface by using equipment such as a mounter (chip component mounting equipment), a device called feeder is needed to supply chip component one-by-one. Today's mainstream feeder system is called a tape feeder. It supplies from a tape rolled in the shape of a reel that holds chip components. However, this system uses paper or resin materials for a tape, with the problem that these materials become waste after use. On the other hand, a bulk packaging system is one which packs chip components individually and puts them into a case, enabling supply of one at a time from the case.

Bypass Capacitor

A capacitor that is connected between the power supply line and ground and performs the role of bypassing high-frequency noise to the ground. Decoupling capacitors are sometimes called bypass capacitors.


CAN (Controller Area Network)

An in-vehicle LAN standard used in the drive, body, and other systems of an automobile.


A capacity that can store an electrical charge. The capacitance of a capacitor increases with the larger area of an electrode, the narrower distance between electrodes, and the higher dielectric constant of the insulator between electrodes. A multilayer ceramic chip capacitor attains a larger area of substantial electrode by layering many electrodes.


One of the three major passive components, together with the resistor and the inductor (coil), it basically consists of two electrodes on both sides of a dielectric (insulating layer). Its capacitance is proportional to the electrode surface area, inversely proportional to the inter electrode distance, and proportional to the dielectric constant of the dielectric. A capacitor has the properties that it can store a charge without conducting a current when direct current voltage is applied, and conducts alternating current. Used in rectification circuits and smoothing circuits of power supply using the property that stores a charge. Also used in filters , impedance matching or noise countermeasures, using its property of conducting an alternating current. The type using a dielectric ceramic such as barium titanate and titanium oxide as a dielectric is called a ceramic capacitor, and the chip type incorporating many electrodes and dielectrics is called a multilayer ceramic chip capacitor (MLCC).

Carrier Tape

A paper or plastic tape used in a feeder system that automatically mounts a chip component by a mounter (chip component mounting equipment). Rolled and packed in a reel shape by taping equipment.


The product name of TDK’s all solid-state batteries.


TDK’s chip varistors (EPCOS brand).


The product name of TDK’s low-temperature plasma generators. Used in ozone generators, ionizers, surface plasma cleaning, and other applications.


A solid-state material of non-metal and mineral manufactured by heat treatment, like ceramic firing. A highly efficient ceramic obtained by precisely adjusting a material with high purity and advanced control in the forming and sintering process is called a new ceramic or a fine ceramic. Among these, one with excellent electromagnetic characteristics is called an electroceramics or an electronic ceramic, and is used as an electronic material.

Ceramic Resonator

Ceramic Transient Voltage Suppressor

A circuit protection element that suppresses high transient voltage such as surges and static electricity.

Chemical Vapor Deposition

Chip Beads

A chip type EMC countermeasure component that absorbs a high-frequency component contained in a signal and converts into heat using the properties of ferrite. To be inserted in a circuit in series. Called beads because they are originally made by penetrating one shaped like a bead with a hole into a lead wire. Enables noise suppression easily without connecting to ground. Widely used in electronic devices.

Chip Varistor

A chip type varistor used as a countermeasure component against surge noise such as static electricity.

Choke Coil

A coil sends direct current, but in the case of current that changes its flux periodically like alternating current, it generates a reaction magnetic flux itself to prevent this (self-induction action in electromagnetic induction). Choke means "to block." As a result of the coil withstanding a reaction magnetic flux, magnetic energy is stored in the coil where an alternating current flows. A coil using this action is called a choke coil. Used in power circuits and DC-DC converters in electronic devices.


A power supply that chops the current using a switching element and converts it to a predetermined voltage with a smoothing or stabilizing circuit. Generally, simple step-down or step-up DC-DC converters are chopper type power supplies. Also called a non-insulated DC-DC converter because it does not use a transformer.

Circuit Protection Element

A device that protects circuits from overvoltage caused by electrostatic discharge (ESG) and surges as well as overcurrent and high temperature. Such elements include voltage protection elements, current protection elements, and temperature protection elements.


A circuit element that guides and circulates the entering radio wave to always a right (or always left) terminal using the physical effect of ferrite called Faraday rotation. Also, isolators used in smartphones and base stations are using the same principle.

Clamp Filter

An EMC countermeasure component to be mounted around a cable to remove noise. Consists of a vertically cut ferrite core of cylinder type.

Cloud Computing

Networking whereby data, application software, and so on are stored and processed on the network cloud (large-scale data centers), rather than on a terminal (such as a PC or smartphone).

CMA (Camera Module Lens Actuator)

A drive mechanism in the camera lens module of a smartphone or other device that adjusts the focus by moving the lands forward and back.

CMOS (Complementary Metal-Oxide Semiconductor)

A semiconductor in which P-type MOS and N-type MOS are connected in a way that they complement each other. Used in the CMOS image sensors of digital cameras and other applications.

Co-generation System

A system that uses electric power generated by an engine or turbine fueled by natural gas, LP gas, oil, or other fuel and recovers the waste heat that is generated for supplying hot water or cooling and heating. Also called combined heat and power. Energy use effects are high, and the systems are also effective for reducing CO2 emissions.

Coercive Force

Magnetic field strength when magnetizing a ferromagnetic material until reaching saturation magnetic flux density, then adding a reverse magnetic field to cancel out the flux density to zero. One of the indexes showing the power of a permanent magnet. One description of this magnetization process in a graph is a B-H curve describing an S-shaped closed curve. Larger product value of residual magnetic flux density and coercive force produces better permanent magnet material.

Common Mode Filter

A countermeasure against common mode noise that has been becoming increasingly important due to the spread of digital equipment and high-frequency transmissions. A common mode filter is an EMC countermeasure component that does not affect the signal in differential mode and absorbs and removes only common mode noise. Used in a connector part to protect the signal quality in high-speed digital interfaces such as USB, IEEE1394, or HDMI. TDK commercially produces common mode filters using three methods; coil method, thick film method, and thin-film method. The demand for use in in-vehicle LAN, such as CAN-BUS, Flex-Ray, MOST and Ethernet, has also been expanding in recent years.

Common Mode Filter for HDMI

Since the signal transmission of a HDMI interface is high-speed differential transmission, a common mode noise is generated from a transmission line. Since the specification of the transmission characteristics for HDMI is defined strictly, an advanced countermeasure against noise is required.

Common Mode Filter for In-Vehicle LAN Compatible with High Temperature

A common mode filter that also withstands high temperature in the engine compartment of an automobile. A noise countermeasure component with an important function ensuring safe operation of automobiles dependent on an electrical network.

Common Mode Noise

A conduction noise that invades through power lines or signal lines has two modes: differential mode (normal mode) and common mode. In differential mode it flows through one lead wire and back through the other, the same as the signal current. In common mode, it flows through two lead wires in the same direction through a floor or ground.


Copper Loss

A power loss due to electric resistance of a coil, as seen in transformers and coils.


A core of a transformer, antenna coil, choke coil, etc. Incorporates soft magnetic materials such as silicon steel, amorphous alloy, and ferrite. A ferrite core is an essential core material in a high-frequency area.

Core Loss

A loss of magnetic energy emitted outside a magnetic field as heat when transformer cores are applied to the field. Known as iron loss in the case of an iron core. Includes eddy current loss and hysteresis loss. Becomes large along with the higher frequency of magnetic field added. Especially eddy current loss increases with the smaller electric resistance of a core material. For this reason, iron group core materials (soft iron and silicon steel etc.) can be used only in a low-frequency area, and ferrite is essential in a high-frequency area. NiZn (nickel zinc) group ferrites have higher electric resistance than MnZn (manganese zinc) group ferrites, and they are used more in high-frequency areas. In a transformer, the sum total of core loss and copper loss due to coil resistance is total loss.

Coreless Coil / Coreless System Inductor

A coil without a magnetic substance core is widely called a coreless coil. In electromagnets, a ferromagnetic material such as iron is used as a core, but iron soon saturates its magnetism with the increase in the current sent through a coil. Therefore, in a superconductive magnet that sends a large current, a coreless coil is used. Moreover, although ferrite is used in transformers of electronic devices or cores of antenna coils, a ferrite core of magnetic material has large loss in a high-frequency GHz band. For this reason, an air cored system inductor is used in high-frequency circuits. Includes those using dielectric ceramics of non-magnetic material with a small dielectric constant as a core, in coreless system inductors.



A head reading element for HDD with a new system that exceeds the limitations of TMR heads. A head for HDD is formed by arraying multiple layers for the recording element and the reading element on a wafer. In order to read the magnetic information in a recording layer, a conventional type GMR head sends a sense current to a thin-film layer (CIP system). The CPP-GMR head attains high sensitivity read exceeding TMR heads by sending this current perpendicularly (CPP system).

CPU (Central Processing Unit)

A component that processes and controls data as the brain of a PC, smartphone, or other device. Also called a processor.


Curie Temperature (Curie Point)

Heating ferromagnetic materials such as iron and ferrite causes them to lose magnetism on reaching a certain temperature (transition to a paramagnetic material). This temperature is the Curie temperature (Curie point). Heating a permanent magnet to more than its Curie temperature also destroys its magnetism. This is called thermal demagnetization.

Current Sensor

A current detection sensor in protection circuits and control circuits of various devices including switching power supplies.

Custom IC

An IC specially designed and manufactured for a specific use/product. An IC partially using a standard design is called a semi-custom IC. Also known as ASIC.


An abbreviation of "chemical vapor deposition." A method used to form a thin-film of products by mixing gas molecules of raw materials in inert gas, having them react on a substrate. The method using a gas reaction in plasma electric discharge is called a plasma CVD method. Used in thin-film processes for semiconductor integrated circuits, heads for HDD, and amorphous silicon solar cells.


Data Center

A facility that houses servers, storage, and other devices to perform centralized processing and storage of massive amounts of data on the Internet.


Direct current. An abbreviation of "direct current."

DC-AC Inverter

A device that converts direct current (DC) input into alternating current (AC) output. Also called an inverter. Used to control the AC motors (induction motors and synchronous motors) used in air conditioners, washing machines, xEVs, industrial machinery, and other equipment and to light cold cathode tubes.

DC-DC Converter

A circuit/device that raises or lowers direct current (DC) voltage. Widely used in mobile computing devices in order to acquire sufficient voltage to drive an IC.

DC-DC Converter for HEV/EV/FCEV

Energy saving/eco-friendly cars, such as the HEV (Hybrid Electric Vehicle), EV (Electric Vehicle), and FCEV (Fuel Cell Electric Vehicle), are driven by a motor using the electric power stored in a main battery. (HEV shares the engine as well). A DC-DC converter for HEV/EV/FCEV functions to convert the high voltage (200-300V) of the main battery of these cars into low voltage (12V etc.) to operate various in-vehicle electrical devices.


Decoupling Capacitor

When the voltage fluctuation in a power supply line becomes large, IC and LSI operation becomes unstable, and interference among circuits becomes a cause of noise. Decoupling capacitors are used to prevent this. Also called bypass capacitors.


Using a high-precision rotary cutter known as a dicing saw to cut semiconductor wafers and make chips (dice).


A chip obtained by dicing (cutting) a disk-shaped semiconductor wafer on which a large number of circuit elements are formed vertically and horizontally. The singular form of dice. A device that mounts a die on a lead frame or substrate is called a die bonder.

Dielectric Ceramic

Ceramic dielectric material. A general term for certain types of ceramics with high dielectric constant such as barium titanate. Used as dielectric materials placed between the electrodes of capacitors.

Dielectric Constant

When placing a dielectric material between two sheets of electrodes, increased charge can be stored by its polarizing action. A dielectric constant expresses how much charge can be stored at this time, and the ratio in the case of assuming the space of electrodes as a vacuum is called a relative dielectric constant. Usually, a dielectric constant indicates a relative dielectric constant. The relative dielectric constant of a barium titanate, that is a high dielectric constant group dielectric, attains even 1,000 to several tens of thousands.

Dielectric Filter

A type of filter formed from a dielectric material with an internal conductor. Mainly used in high-frequency circuits.

Dielectric Material

An insulator that does not conduct current. When placed in an electric field, it polarizes to plus and minus (dielectric polarization).

Different Materials Simultaneous Firing Technology

TDK's original technology, used to laminate and fire sheets with different dielectric constants simultaneously. Requires a very high technology and knowhow in material design and firing process, such as securing high dimensional accuracy or preventing warpage problems due to different thermal expansion coefficients.

Differential Mode Noise

Noise in differential mode (also called normal mode) that flows through two lead wires, one as outward and another as return, the same as a signal current. Generally, a differential mode noise exists in a higher frequency range than a signal frequency, therefore a capacitor, chip beads, and an LPF (low pass filter) are used for the noise suppression. A three-terminal filter with a steep frequency characteristic is used when the frequency bands of noise and signal are close.

Differential Transmission System

A system that transmits two signals in which the phase is different by 180 degrees through two lines, not a data transmission of signal by single line (and ground). Also called a balanced transmission system. High-speed digital interfaces such as USB, IEEE1394, and HDMI incorporate a differential transmission system. Although it has the advantage of not being easily influenced by noise, common mode noise is in fact generated due to the slight unbalance of a differential signal, etc. For this reason, a common mode filter is used in high-speed digital interfaces.


An element that functions to separate a radio wave into the frequency band of each system at the entrance of an antenna circuit in multiband devices like smartphones where phone call services through two or more systems can be used by using one set of a terminal. An LC compound component that combines an LPF (low pass filter) and an HPF (high pass filter).

Direct Current (DC)

A current that flows in one direction, from a plus pole to a minus pole, as in a dry cell or a battery.

Direct Current Resistance (Rdc)

A resistance (R) in the case of sending a direct current (DC) through a circuit element.

Direct Current Stabilizing Power Supply

A power supply that stabilizes unstable, variable direct current to a uniform voltage. A DC-DC converters is a representative direct current stabilizing power supply. Switching power supplies consist of a rectification circuit and a direct current stabilization circuit.

Direct Current Superposition Property

When a current flowing through a coil wound around the core of a magnetic material such as a ferrite is enlarged, a flux density that a coil generates is increased, and eventually the core reaches its saturation state and looses the properties as a coil. A direct current superposition property is one that shows a relationship between a direct current that flows into a coil and an inductance.

Directional Coupler

A component that controls the output gains of transmission amplifiers automatically by feeding some outputs back in transmission circuits of wireless communication devices such as smartphones. Enables functions by efficiently combining two inductors and the peripheral capacitor components.

Discrete Components

Individual electronic components such as capacitors, inductors, and diodes. This term is used in contrast to devices and modules, which are combinations of multiple components.

Discrete Track Medium

DTM (discrete track media). The conventional magnetic recording medium for HDD had a problem that magnetic interference from adjacent tracks becomes larger with the narrower track width resulting from improvements in recording density. A discrete track medium essentially solves this problem, enabling remarkable improvement in recording density. By forming a slight slot of a single nanometer in depth in the magnetic layer, it enables physical separation of the recording track, which reduces the magnetic interference of adjacent tracks.


A pulse-height discriminator. An element that senses a pulse signal above a prescribed level.

Distributed Power Supply System

On the power grid, a power supply system that is regionally distributed and has low transmission loss such as a smart grid. In electronic devices, a method of stepping down high input voltage to an intermediate voltage and then stepping it down further to the operating voltage of an IC or other component. Also called distributed power supply.

Door Open/Shut Sensor

A sensor with functions to adsorb and hold door/lid using magnetic energies as well as to turn an electric contact ON/OFF through a built-in reed switch when opening and shutting. Features high reliability by using a reed switch. Includes one type that turns an electric contact OFF when adsorbing through a magnet, and another type that turns ON. Used as an open/shut sensor for a door or a lid in OA equipment, such as copy machines and printers, FA equipment, etc.

DRIE (Deep Reaction Ion Etching)

An etching technology used for MEMS and other devices. Capable of manufacturing ultra-high-precision microstructures with high aspect ratios.



Variation from a set standard value. For example, fluctuation in the output voltage of a sensor due to changes in the ambient temperature is called thermal drift.


A key device to share reception and transmission via one antenna in wireless communication devices like smartphones. It functions to share an antenna element by combining a BPF (band pass filter), and separating transmission waves and reception waves. Conventionally, a dielectric duplexer has been used, but today, a smaller and lighter SAW duplexer or BAW duplexer using the oscillation of a piezoelectric element is mainly used.

Dust Core

A core (magnetic core) manufactured by compression molding of a soft magnetic metal powder such as sendust. Also called a powder core or powder magnetic core. Since it is made of a metal material, it has lower electrical resistance than a ferrite core.


Abbreviation for digital transformation. Approaches and initiatives that seek to transform lifestyles and business styles to make them more enriching and better through the use of various digital technologies.



An abbreviation of "electronic control unit" used for automobile electronic control. ECUs were originally used mainly for engine control, then came to be used for various electronic system controls, such as drive systems, body systems, safety systems, and multimedia systems (information and telecommunications systems). From 30 to 40 in general, and over 100 in case of a luxury car, ECUs are incorporated in recent computerized automobiles, and these are networked by an in-vehicle LAN.

Eddy Current

A spiral current generated by electromagnetic induction when the magnetic field applied to a conductive substance, such as metal, changes. When a high frequency magnetic field is applied, the metal heats up due to the Joule heat of the eddy current. Induction cookers and IH rice cookers utilize this phenomenon, but transformers and other devices experience core loss (heat loss) called eddy current loss.

Edge Computing

There are concerns that the data processing capacity of cloud computing, in which data is transmitted to servers in a data center for centralized processing, will not be able to keep up with the rapidly increasing volume of data. To solve this problem, edge computing is a networking technique whereby servers are distributed at the edges of systems near user terminals for data processing.


Electric Double Layer Capacitor

An energy storage device having a similar structure to a capacitor that has an activated carbon electrode dipped in an electrolytic solution. Activated carbon with countless holes has a very substantial surface area, enabling a capacity more than 1 million times (farad order) as large as a conventional electrolytic capacitor (microfarad order). Has been considered an extensive application as auxiliary power that supplies a temporary and large current to the drive motor of xEVs, or variational adjustment of outputs of solar or wind power generation.


A fine ceramics material with electromagnetic characteristics. Examples include ferrite in transformer cores or magnet materials, dielectric ceramics used in capacitors, piezoelectric ceramics used in oscillators or filters and semiconductive ceramics used in temperature sensors or varistors. Requires advanced technology in processes such as material design, molding, and firing.


A substance that ionizes cations and anions in a solvent such as water, facilitating electrical conductivity. Batteries generally use liquid electrolytes, but all solid-state batteries use solid electrolytes.

Electrolytic Capacitor

A capacitor using a metal oxide and an electrolyte solution, or a solid electrolyte. Features plus/minus polarity and large capacitance. Includes an aluminum electrolytic capacitor, a tantalum electrolytic capacitor, etc.

Electromagnetic Buzzer

A sound generator combining a magnet, a coil, a diaphragm, etc. Features a wide frequency and a high sound pressure, enabling it to play melodies. Widely used as alarm sounds generating devices of home electric appliances, OA equipment and vending machines and so on.

Electromagnetic Induction

An action that is widely used in motors, generators, transformers, induction heating, and other applications. When a magnet is moved inside and outside of the proximity of a coil, for example, electromotive force (voltage) is induced in the coil as the magnetic flux changes, current flows, and magnetic flux is generated. This is referred to as electromagnetic induction. Inductance is the numerical value indicating how much magnetic flux a coil can generate at such a time.

Electromagnetic Shield Material

A material used to block electromagnetic. TDK's Flexield is a compound electromagnetic shield material, mixing magnetic material with high magnetic permeability into a resin, in thin and flexible form, enabling highly adaptable processing.

Electronic Buzzer

A small sound converter called a sound generator or a sounducer. Includes a piezoelectric buzzer using a piezoelectric element and an electromagnetic buzzer using a magnet.

Embedded Motor Controller

An embedded compact motor controller used to drive and control brush-type DC motors, brushless DC motors, steppers, and other equipment.

EMC (Electromagnetic Compatibility)

An abbreviation of "electromagnetic compatibility/electromagnetic coexistence nature." Generally used to signify noise problems in electronic equipment. Electronic equipment not only suffers damage due to noise, but serves as a source of the noise itself. Therefore, since a digital technology has been developed and trouble due to noise now occurs frequently, in addition to EMI (electromagnetic interference = emission problem), the concept of EMS (electromagnetic interference susceptibility = immunity problem) has appeared. EMC (electromagnetic compatibility) is to attempt to reconcile EMI and EMS. That is, EMC is based on the concept of "not emitting noise affecting another system" as well as "not receiving noise influence from another system." An EMC countermeasure component is used for the countermeasure.

EMC Countermeasure Components

A general term used for a noise countermeasure component such as a capacitor, an inductor, chip beads, a varistor, a three-terminal filter, a common mode filter, a ferrite or a noise suppression sheet (TDK's Flexield).


Electromagnetic interference.


Electromagnetic interference susceptibility.

Energy Harvesting

Also called environmental power generation. A technology that harvests energy such as heat, light, and vibration in the surrounding environment and converts it into electric power for use.

Environmental Power Generation


Equivalent series capacitance. A capacitor component that does not exist in a circuit diagram is distributed in the coils or terminal electrodes of an inductor or a resistor. Such a capacitor component when inserted in a circuit is called an "equivalent series capacitance." Requires an inductor of low ESC in a high-frequency area.


Equivalent series inductance. Parts, lead wires, and wiring patterns, such as a resistor or a capacitor, also have slight coil effect. This is called equivalent series inductance. It acts as an LC filter and becomes a cause of loss in a high-frequency area.


Equivalent series resistance. An inductor and a capacitor have a DC resistance component (Rdc) due to the resistance of an internal electrode or a terminal electrode. A substantial resistance when inserting in a circuit is called "equivalent series resistance." Requires an inductor and a capacitor of especially low ESR in a high-frequency range.


A method used to form a detailed pattern on a material surface. Methods include the wet etching method using an acid and other etching reagent, the dry etching method using plasma, and the ion milling method using an ion beam. An absolutely necessary technology for thin-film processes of semiconductor integrated circuits, such as IC and LSI, MEMS devices and heads for HDD.


Ideas or efforts to transform the entire energy field to save more energy and develop a decarbonized society through the use of renewable energy and storage systems and promoting smart grids, HEMS, and xEVs.


The product name of TDK’s magnetic necklace.

Eye Pattern

A method used to assess whether the differential signal of a digital high speed interface, such as USB, IEEE 1394, and HDMI, is transmitted without waveform distortion. Called "eye pattern", because the form of transmission waveform and central red hexagon resembles a series of eyes. Signal waveform should not appear within the area of a hexagon when a noise countermeasure component such as a common mode filter is inserted.



A company that specializes in design and development and does not have its own production facilities such as factories. The advantages of fabless operation include higher production efficiency and lower costs.

FCV/FCEV (Fuel Cell Electric Vehicle)

A type of Electric Vehicle (xEV). The vehicle is equipped with a hydrogen tank and uses the chemical reaction between oxygen in the air and hydrogen (the opposite reaction of electrolysis of water) to generate electric power and drive a motor. Since there is no need for an external electric power supply, and they emit only water, fuel cell vehicles are also called the ultimate eco-cars for a decarbonized society.

Feed Through Capacitor

A capacitor with its high-frequency characteristics improved by attaining low ESL (equivalent series inductance). A capacitor, slightly but including its internal electrode or terminal electrode, acts as an inductor, and in digital equipment, the higher-harmonic component (frequency component multiplied by integral number to a fundamental wave) contained in a digital signal serves as noise and emits noise. In order to solve this problem, a feed through capacitor was developed with three terminals structure incorporating ground.


A near field communications (NFC) standard (type F) used for contactless IC cards (such as Suica and PASMO cards used for public transportation) and electronic money.


An oxide group magnetic material blending and sintering manganese, nickel, zinc, etc., to iron oxide. Trivalent metal ions and divalent metal ions are arranged in a grid of oxygen ions, and as a result of interplay between those magnetic forces, a magnetism peculiar to ferrite, called ferrimagnetism appears. It includes some types according to crystal structure. A hard ferrite with hard magnetism is used in ferrite magnets, and a soft ferrite with soft magnetism is used in core materials of transformers, antenna coils, choke coils, and common mode filters. Generally, ferrite indicates a soft ferrite. A typical soft ferrite includes manganese zinc (Mn-Zn) group ferrite and nickel zinc (Ni-Zn) group ferrite.

Ferrite Core

The core of a ferrite used in transformers, antenna coils, choke coils, common mode filters, etc. Invented in Japan in 1932 and commercialized by the Tokyo Denki Kagaku Kogyo K.K. that is the predecessor of TDK. When a metal group soft magnetic material is used as a core material, the calorific loss due to an eddy current becomes large in a high-frequency range. On the other hand, since a ferrite that is a metal oxide has a large electric resistance with few calorific losses due to an eddy current, it is essential as a core material in a high-frequency range. Various properties include a high magnetic permeability (high µ), a low core loss, a high property in wide temperature range, etc. Especially, a ferrite used as core materials of transformers or choke coils in power circuits operating with a large current is called a power ferrite.

Ferrite for ADSL Modem Transformer

In xDSL including ADSL that transmits sound and high-speed data simultaneously using a telephone line, the quality of the ferrite material used for the transformer core in the modem is very important.

Ferrite for Pulse Transformer for LAN

Ferrite used as core material of pulse transformers in LAN systems.

Ferrite Magnet

A magnet manufactured by forming and sintering powder materials consisting mainly of iron oxides. Excels in cost performance and accounts for about 80% or more of the magnet production volume in the worldwide magnet industry by weight.

Ferromagnetic Material

Briefly described, this is a substance that sticks to a magnet. Also simply called a magnetic substance or a magnetic material. Ferromagnetic are roughly classified into a hard magnetic material that maintains its magnetization when the magnet field is removed, and a soft magnetic material that returns to its original state when the magnetic field is removed. Magnet steel used in permanent magnets and hard ferrite are hard magnetic materials, and soft iron, as well as silicon steel board, sendust, permalloy, and soft ferrite used for transformer cores, are soft magnetic materials. Generally, a ferrite indicates a soft ferrite.


Firing Atmosphere

An ambient gas used in the case of firing a ferrite core and a multilayer ceramic chip capacitor in a furnace. For example, called a nitrogen atmosphere in the case of providing nitrogen in order to control oxidization. Requires an advanced knowhow and technology in atmosphere control as well as temperature control.

Five G (5G)

A fifth-generation mobile communications system. Spreading as the successor, next-generation communications infrastructure following existing LTE and 4G since about 2019. Features include high speed, high capacity, low latency, and multiple simultaneous connections.

Flash Memory

A type of non-volatile semiconductor memory.


The name of TDK’s Ag-stacked transparent conductive film product. A functional film with a thin Ag alloy film uniformly formed on a plastic film substrate.


A compound electromagnetic shield material with sheet shape that is thin and flexible with excellent processability to any required form by mixing magnetic materials with high magnetic permeability into resin. Flexield is a registered trademark of TDK Corporation. It suppresses radiation noise from electronic devices over a high frequency range, with excellent performance especially in the high-frequency range. A sheet-shaped noise counter-measure component best suited to laptop computers, digital still cameras, and portable devices such as cellular phones.

Flex Ray

A type of in-vehicle LAN with high-speed and hi-reliability, compatible with the X-by-Wire system that controls steering or brakes by electrical impulses.

Flip Chip Mounting System

A device that mounts ICs and LSI as bare chips (dies) onto a substrate with high precision is called a die bonder, and among these devices, a system device that inverts (flips) the bare chips so that the electrodes (pads) on the surface face downward and directly bonds them to the circuit board is called a flip chip mounting system. Ultrasonic vibration is used for bonding. Compared to the wire bonding method, mounting area is substantially decreased, enabling circuit boards to be smaller.

Flip Chip/Flip Chip Bonder/Flip Chip Mounter

Flow Soldering

A kind of soldering method. A method of joining components in which a printed circuit board with electronic components (primarily components with leads) is passed over a solder bath filled with molten solder, and the solder is sprayed to join the components.

Flyback Transformer

A step-up transformer for accelerating the electron beam emitted by the electron gun of a cathode ray tube.

Forty-eight (48) V Power Supply

Conventional 12 V automobile batteries are used to operate electrical equipment, and 12 V power supplies raise the voltage to 48 V, which is safe to the human body. Used in mild hybrid electric vehicles (MHEVs).

Forward System/Flyback System

A circuit system for switching power supply. A forward system sends energy to output when a switching element is ON, and a flyback system sends when it is OFF.


A company that specializes only in manufacturing that is outsourced by other companies (such as fabless makers). In the semiconductor industry, the division of labor between fabless makers and foundries is progressing.


In manufacturing of semiconductor devices, when transferring wafers automatically one after another to various manufacturing equipment, wafers are stored in sealed containers so that particles (fine dust) would not adhere. This container is called a FOUP.

Four K/ Eight K (4K/8K)

Television resolutions. 4K means that the number of horizontal pixels is approximately 4,000, and 8K means that the number is approximately 8,000 pixels. Terrestrial digital full HD broadcasts have approximately 2,000 (2K) horizontal pixels, and a 4K screen of the same size will have four times as many pixels, while an 8K screen of the same size will have 16 times as many pixels, achieving ultrahigh-resolution. Super Hi-Vision (SHV) researched and developed by NHK is equivalent to 8K. Internationally also referred to as Ultrahigh Definition Television (UHDTV).

FPGA (Field-Programmable Gate Array)

An integrated circuit whose logical circuit configuration can be rewritten in the field.

Front End Module

A miniaturized module by unifying circuits (an antenna switching device, a diplexer, an LPF, etc.) to pretreat signals received from antennas, such as switching of transmitting/receiving or separating frequencies, in wireless communication equipment like smartphones.

FTTH (Fiber to the Home)

A high-speed digital data communications technology that uses optical fiber. Higher speeds and larger capacity communications are possible compared to xDSL and other methods that use metal wire.

Functional Film

A film in which a thin film with various functions is formed on the surface of a plastic film as a base material by coating, vacuum vapor deposition, sputtering, or other technique. Transparent conductive film such as ITO films are used for touch panels and other applications.

GBDriver (Gigabyte Driver)

A controller LSI controlling a NAND type flash memory. GBDriver is a registered trademark of TDK Corporation.

Gear Tooth Sensor

A type of rotation sensor. A device that uses Hall sensors and other components to change the magnetic field from a magnet according to the gear tooth of a rotating gear. Used to measure the rotation speed (number), crank angle, cam angle, and other characteristics of automobile engines.

Giant Magnetoresistance (GMR) Effect

Giant-Magnetostriction Element

The phenomenon that a ferromagnetic material such as iron and ferrite is distorted while its appearance is slightly expanded in the case of a magnetic field being applied to magnetize it, is called magnetostriction (magnetic strain). A giant-magnetostriction element is a material with a bigger expansion degree of approx. 1000 times greater than the usual ferromagnetic material. Although a piezoelectric material also shows a similar deformation according to voltage, a giant-magnetostriction element has not only a large dimensional change, but also features a high-speed response/high energy conversion capacity.

Gigaspira Inductor

In a chip conductor with conventional structure, a stray capacitance (capacitor component) is generated between terminal electrode and internal terminal, and that lowers self-resonance frequency (SRF) in a high-frequency area. In order to solve this problem, the terminal electrode and an inner conductor of spiral shape are laminated in a longitudinal direction. Has an inductor structure without vertical and horizontal directivity, attaining stray capacitance reduction.

GMR Head

A mainstream magnetic head for reading used in HDDs during the 1990s and the 2000s. GMR is an abbreviation of "giant-magnetoresistance effect", that is a reading principle. Heads for HDDs are manufactured by forming a thin-film to a reading head and a recording head on a wafer, using thin-film process technology. Visualizing a hard disk as paper and a recording head as a pen, a thinner brush can write finer characters and recording density is also improved, but in order to read a weak magnetic charge recorded on a magnetic layer, one with higher sensitivity than a reading head is required. However, the conventional type of GMR head has limited capability to record in higher density. For this reason, the TMR head and the CPP-GMR head were developed as a new reading element, as well as the PMR head as a recording element.

Grain Boundary

A boundary containing many crystal grains in polycrystalline materials is called a grain boundary. This grain boundary is deeply involved with electromagnetic characteristics of ceramics or ferrites.

Green Sheet

A thin sheet that serves as a base material to add an electrode or a conductor pattern in the manufacture of multilayer chip components using the sheet method. A green sheet indicates a raw sheet before firing. In the manufacture of multilayer ceramic chip capacitors, a binder is added to dielectric ceramics powder to make a pasty slurry, and this is spread thinly on a carrier film before drying. This is used as a green sheet.

Gyro Sensor

An angular velocity sensor. When a rotational motion is applied to a moving object, inertial force called the Coriolis force acts. A gyro sensor is a sensor that calculates the angular velocity (rotational velocity) by measuring this Coriolis force. An inertial sensor consists of an acceleration sensor and a gyro sensor.


Hall Effect

A type of galvanomagnetic effect. A phenomenon in which voltage is generated orthogonally to both the current and the magnetic field when a magnetic field is applied to a conductor through which current is flowing. Called the Hall effect for its discoverer.

Hall Sensor/Hall IC

A magnetic sensor that uses the Hall effect to detect the strength and direction of a magnetic field. There are various types. The component that integrates a Hall sensor with an operational amplifier, amplifies the signal, and outputs it is called a Hall IC.

Hall Switch

A type of Hall sensor that detects the strength of a magnetic field using the Hall effect, compares it with a set threshold value, and performs a switching operation.

HAMR (Heat-Assisted Magnetic Recording)

A new technology for raising the recording density of HDDs. A method in which the fine magnets in the recording layer over magnetic disk are spot-heated with laser light only when data is written, making it easy for magnetization to be reversed for magnetic recording. A method that uses microwaves instead of lasers is called microwave-assisted magnetic recording (MAMR).


Tactile technology. Technology that uses vibration, movement, and so on to re-create virtual sensations for users.

Hard Magnetism


The frequency component that is an integral multiple of the fundamental wave. May be noise.


Hard disk drive. Conventionally used as a recording device in personal computers, HDD recorders and a server in a data center. Also, small-sized HDDs are used in digital portable music players and so on. Consists of components including a magnetic disk, a platter (a disk having a special magnetic metal thin-film as a record layer) as a magnetic recording medium, a spindle motor that rotates the disk at high speed, a magnetic head that records and reads signals, and a VCM (voice coil motor) to drive the magnetic head.


A high-speed interface that transmits the mass digital image and sound data of Hi-Vision, etc. A digital appliance like television and an audiovisual equipment like a DVD recorder can be connected by one cable.

HDTV(High Definition Television)

Over approximately 10 years starting in about 2000, terrestrial television broadcasts around the world have transitioned from analog to digital television (terrestrial digital television). The televisions with standard picture quality (4:3 aspect ratio) used until then are called SDTV, and televisions with high resolution such as Hi-Vision are called HDTV (16:9 aspect ratio). The resolution of full spec HDTV (full HD) is 1920 × 1080 pixels, and since it has horizontal resolution of approximately 2,000 pixels, it is referred to as 2K television. A transition is now being made to even higher resolution 4K television and 8K television (UHDTV). NHK’s Super Hi-Vision (SHV) is equivalent to 8K television.

Head for HDD

Magnetic head of HDD (hard disk drive) used as a memory device in personal computers and HDD recorders. Manufactured by laminating a thin-film to a recording element to write information in a magnetic recording medium (magnetic disk called platter) and a reading element to read information, on a wafer. A combined device consists of a chip (called a slider), acquired by cutting a wafer, attached to an arm or a suspension is called as a head gimbal assembly (HGA).

HEMS (Home Energy Management System)

A system for the efficient use of household energy, such as power consumption by home appliances and the power generated by solar panels.

HF (High-Frequency)


An alternating current or a radio wave with high-frequency. Abbreviated as HF. There is no clear definition, but generally indicates several kilohertz or higher in the context of electric power and several tens of megahertz (ultra-shortwave and higher high frequency) in the context of communications.

High-Frequency Component/Device

A component/device used in high-frequency circuits of communication devices including smartphones, etc.

High Pass Filter (HPF)

High-Temperature Compatible Automotive Components

Electronic components that can withstand the high temperature in an automobile engine compartment and so on. Components include high-temperature compatible multilayer ceramic chip capacitors, high-temperature compatible inductors, and high-temperature compatible common-mode filters for in-vehicle LANs.


HPF (High Pass Filter)

Hybrid Thin-Film Multilayer Method

A method used to incorporate passive components such as two or more capacitors and inductors by layering substrates such as dielectric ceramics, in the production of Low Temperature Co-fired Ceramic (LTCC) etc. Enables reduction of areas or volumes of substrates, adopted as manufacturing processes of several types of modular components.


A phenomenon where the state of a substance retains a history of the effects that were applied to it in the past. A representative example is the magnetic history phenomenon of ferromagnets. A graph of hysteresis is called the hysteresis curve (B-H curve).



An abbreviation of "integrated circuit." A compound circuit component combining many active elements, such as transistors and diodes, and passive elements, such as a capacitors and resistors, on a substrate such as a silicon semiconductor substrate. An IC containing from 1,000 to 100,000 electronic components per chip is called "LSI" (large-scale integration). The various types are roughly classified according to function, into digital ICs (memory IC, logic IC, etc.) that process digital signals and analog ICs for analog signal processing used in operational amplifiers, power IC, communication IC etc.

IEEE Milestone

A commendation system of the U.S.-based Institute of Electrical and Electronics Engineers (IEEE) for recognizing those innovations achieved in electrical, electronic, information, and communication related fields that have contributed to the development of society or industry. The system was established in 1983. In 2009, the discovery of ferrite and its commercialization by the Tokyo Institute of Technology and TDK was recognized as the 89th IEEE Milestone in the world.


A standard of high-speed serial interface standardized by IEEE (Institute of Electrical and Electronics Engineers). Used for fast transfer of image and sound data, and adopted as an interface in AV equipment such as personal computers and video cameras.

IGBT (Insulated Gate Bipolar Transistor)

A power semiconductor device that integrates the functions of a MOSFET and bipolar transistor. Used in power conversion equipment compatible with high current such as the inverters used to control motors in xEVs and industrial equipment.


Electric resistance in AC circuits. In alternating current, capacitors and inductors also have an impedance according to frequency.

Impedance Matching

Impedance matching is necessary to make the impedances (electric resistance in alternating current) of signal transmission side and reception side the same, by adjustment (matching). If the impedances of signal source and of load side are mismatched, reflection and loss of signal will occur. In order to prevent this, an inductor or a capacitor is inserted to match the impedances. Impedance matching is especially important in a high-frequency circuit.

IMU (Inertial Measurement Unit)

A motion/gesture-based device that integrates an acceleration sensor or gyro sensor (angular velocity sensor) with a magnetic sensor (compass), barometric pressure sensor, or other components to measure movement, pose, position, and other attributes.


A coil sends direct current smoothly, but in the case of current that changes like alternating current, it generates reverse voltage to prevent current change through the mechanism of electromagnetic induction, and serves as a resistor. This is called inductance. Since inductance is proportional to an alternating current frequency, even a coil with few numbers of turns has a large resistance(impedance) in a high-frequency area.

Induction Heating

A method of heating that uses Joule heating from eddy currents associated with electromagnetic induction. The principle of electromagnetic cooking equipment and high-frequency quenching.

Inductive Device

Devices that make use of the characteristics of a coil, such as inductors and transformers.


Inductors are roughly classified into the coil type, with the lead wire in the shape of a coil, the multilayer type that prints and accumulates a coil pattern on a sheet, and the thin-film type, in which a coil pattern is formed on a wafer by using a thin-film process technology. They are also classified according to use, into power supply systems, general signal systems, and high-frequency systems. In power supply systems operating with a large current, the coil type using a copper wire is mainly used. An inductor of general signal system is used in LC filters and resonance circuits that classify only specific frequency, and a multilayer chip type is mainly used where small sizing/thin shaping is required. For an inductor in a high-frequency system, impedance matching in high-frequency circuits is a major application.

Inertial Navigation System (INS)

"A system that automatically navigates aircraft, ships, and so on by calculating attitude, direction, speed, position, and so on based on information from inertial sensors (gyro sensors and acceleration sensors) and the Global Navigation Satellite System (GNSS).
Car navigation systems were developed as the automobile versions of such systems."

Inertial Sensor

When an external force is applied to an object that is stationary or is moving in a straight line at a constant velocity, the inertial force acts according to the law of inertia. An inertial sensor, which consists of an acceleration sensor and a gyro sensor (angular velocity sensor), detects this.

Inrush Current

The massive current that momentarily flows in when a power supply switch is turned on. Inrush current can cause circuit breakers to trip and failure of devices, so protective elements and protective circuits are used.

Insulated DC-DC Converter

A DC-DC converter that uses a transformer to electrically insulate the primary and secondary sides.


A network providing the same environment as Internet within a company or a research institute, conducting data transmission, and sharing information via E-mail and other tools.

In-Vehicle LAN

A system that networks various electrical equipment and devices in automobiles. Broadly categorized as drive systems (powertrain systems), body systems, safety systems, and multimedia systems (information and communication systems). The main body system is CAN, the main drive and safety systems are CAN and FlexRay, and the main multimedia systems are Most and Ethernet.


A device that changes direct current into alternating current of arbitrary voltage or frequency. Inverters are used for rotation speed control in xEVs, industrial machinery motors, and compressor motors in air conditioners and refrigerators as well as in LED power supplies.


TDK’s energy harvesting sensor module. The device uses the rotation of an automobile tire and so on to sense tire pressure and other data based on the electric power generated by a piezoelectric element.


IoT is an abbreviation of Internet of Things, which uses the Internet to connect various objects such as electronic devices, furniture, and office supplies. A further advancement of this is the IoE, or Internet of Everything, which will connect all things.

Ion Milling

A technology used to form a detailed pattern on a material surface by using a high-speed ion beam in vacuum. Used in manufacturing of semiconductor integrated circuits, heads for HDDs or MEMS devices.

Iron Loss


In wireless communication devices such as smartphones and base stations, some signals coming from the antenna reflect in the internal circuitry and flow backwards. An isolator functions to isolate and remove this backflow component to protect circuits and stabilize operation. It adapts the nonreversible principle of a radio wave called Faraday rotation. The magnetic field of a magnet and a special ferrite are used in isolators.

Isotropic Magnet

ITO (Indium Tin Oxide)

A transparent electric conduction film made of indium oxide/tin oxide. Used in touch panels, etc.


Knock Sensor

A sensor that detects abnormal combustion (knocking) of engines.


LaCo (Lanthanum-Cobalt) Ferrite Magnet

A ferrite magnet provided with the world top class characteristics by adding La (lanthanum) and Co (cobalt) to base materials of Sr (strontium) ferrite magnets.


An abbreviation of "local area network." A network that connects computers, printers, servers, etc., through high-speed lines within offices, research institutes, schools, and so on. One using wireless communications is called a wireless LAN.

LC Filter

A filter circuit incorporating an inductor (L) and a capacitor (C). Includes a low pass filter (LPF) that passes below specific frequency, a high pass filter (HPF) that passes more than specific frequency, and a band pass filter (BPF) that passes only a specific frequency band, and notch filter (NF) that blocks a specific band of frequencies. Although a filter can be made by combining a capacitor (C) and a resistor (R), using an inductor enables to have a steep attenuation characteristic, attaining a filter of small loss. A three-terminal filter is an EMC countermeasure component grouping elements such as an inductor and a capacitor into one component, to attain high characteristics.


An abbreviation of "liquid crystal display."

Lead-Free Piezoelectric Ceramics

A type of piezoelectric ceramics that does not contain lead. Piezoelectric ceramics such as lead zirconate titanate (PZT) contain lead, which is harmful to humans and the environment, so new materials with the same characteristics that do not contain lead have been developed.

Lead-Free Solder

Solder is an alloy of lead and tin. Since lead is harmful to humans and the environment, lead-free solder, which does not contain lead is now used for bonding electronic components. The melting point is higher than that of conventional solder, so care must be exercised regarding thermal damage to electronic components.


An abbreviation of "light emitting diode." Often used in lighting apparatus and back lights of liquid crystal displays (LCD) of personal computers and smartphones, etc.

Linear Power Supply

An AC-DC power supply that converts commercial alternating current to stable direct current using the linear method or the switching method. A power supply that uses a power supply transformer to step down and then rectify a smooth commercial alternating current to obtain stable direct current is a linear power supply. Inferior to switching power supply in terms of size, weight, and efficiency, but features low noise and excellent stability.

Lithium Ion Battery

A secondary battery that uses a lithium compound as the cathode and graphite as the anode and charges and discharges through the movement of lithium ions. Broadly used as the batteries in smartphones, notebook PCs, Electric Vehicles (xEV), and other devices.


A general term referring to the consumption of electrical energy by resistance, motors, and so on.

Load port

A device that is equivalent to a door (interface) part in the case of conveying wafers in and out between semiconductor devices and Front Opening Unified Pods (FOUPs.)

Low Temperature Co-Fired Multilayer Substrate

LPF (Low Pass Filter)


An abbreviation of "large-scale integration." Components contained per chip are from 1,000 to 100,000, greatly exceeding IC (integrated circuit). One containing from 100,000 to 10 million electronic components per chip is called VLSI (very large-scale integration). Mainly produced as a mass memory chip, a high-performance processor (MPU), etc.

LTCC (Low Temperature Co-fired Ceramic)

A modularization technology used to print and multi-layer the circuit consisting of many elements such as a capacitor and an inductor, on a dielectric sheet (glass ceramic based on alumina). Saves more space than packing elements into a printed circuit board in a high density.


MAMR (Microwave-Assisted Magnetic Recording)

A new technology that increases the recording density of HDDs. A method of magnetic recording where the disk is irradiated with microwaves only when data is being written to create a state where magnetization reversal is easy.


A permanent magnet. Although there are alnico magnets made of metals, ferrite magnets, rare earth permanent magnets (neodymium magnet etc.), and bond magnets made by mixing those powders into materials such as plastic or rubber, are mainstreams.

Magnetic Field Resonance Method

A method of wireless power transfer. A transmission coil and a receiving coil are connected to a capacitor and the LC resonance phenomenon is used for contactless electric power transfer. Features include a power transmission range that is larger than that of the electromagnetic induction method, and the ability to efficiently transfer power even if the gap between or positions of the transmission coil and receiving coil are misaligned.

Magnetic Head

An element that records and reads sound/image/data information to a magnetic recording media such as a magnetic tape or a magnetic disk. Although a bulk head for processed magnetic material such as a ferrite was used in tape recorders or VTRs, heads for HDD are manufactured by forming a thin-film to a recording element and a reading element on a wafer, using thin-film processing technology.

Magnetic History Curve

Magnetic Material

A general term for materials that show certain magnetism to non-magnetic materials that does not change to an external magnetic field. Includes ferromagnetic, paramagnetic, diamagnetic, and other materials, but generally, a magnetic material indicates a ferromagnetic material.

Magnetic Sheet

A magnetic shield material that is processed into a flexible sheet by mixing an ultrafine powder of a soft magnetic metal in resin. The sheets can be cut into any shape, and they are used as an easy and effective countermeasure product against radiated noise.


Magnetite and its constituent triiron tetraoxide (Fe3O4).

Magnetoresistance (MR) Effect

A phenomenon whereby electric resistance changes slightly when a magnetic field is applied to a ferromagnetic material. The MR head that was the mainstream of reading elements for HDD in the 1990s practically applied this phenomenon as a thin-film product of ferromagnetic materials. Later, it was discovered that a larger effect can be acquired by using a special multilayer thin-film. This was named the giant magnetoresistance (GMR) effect and was commercialized in the form of GMR heads. In addition, TMR heads, which make use of the tunneling magnetoresistance effect was also developed. Today, the reading elements of mainstream HDD heads are TMR heads. TMR elements are also used in magnetic sensors and angle sensors.


Also called magnetic distortion. A phenomenon that the outer shape of a ferromagnetic material is slightly expanded and distorted in the case that a magnetic field is applied for magnetization. Giant-magnetostriction element is a new material; its dimension changes approx. 1000 or more times than usual ferromagnetic materials.

Maximum Energy Product

Medium-Voltage Chip Capacitor

A compact chip capacitor designed to withstand high voltage, from one hundred to six hundred volts.


A product with enhanced vibration and heat resistance formed by bonding metal terminals to the external terminals of a multilayer ceramic chip capacitor (MLCC). Used in in-vehicle electrical equipment and other applications.

MEMS (Micro-Electro-Mechanical System)

A technology that integrates actuators, sensors, circuits, and other components on a single board. Also called micro-machining. Manufacturing is performed using thin-film processing technology and multilayering methods. In addition to sensors such as acceleration sensors, angular velocity sensors, pressure sensors, and MEMS microphones, the print heads of inkjet printers and the servo mechanisms of HDD heads are also products that apply MEMS technology

MEMS Sensor

A sensor manufactured using MEMS technology. TDK offers a diverse and wide range of MEMS products including MEMS microphones, MEMS pressure sensors, MEMS ultrasonic sensors, integrated sensors (inertial sensors, motion sensors, IMU) and sensor modules that combine MEMS acceleration sensors, MEMS gyro sensors, and other sensors.

Micro Machining

A technology for manufacturing actuators, sensors, structural materials, and other devices on the micron order using a MEMS crafting technique that employs semiconductor processing technology.


Consists of one or more LSIs (large scale integration) incorporated with a CPU (central processing unit), a memory, and a peripheral circuit. Incorporated in many home electronics including personal computers.


Electromagnetic waves with a wavelength of 1 m to 1 mm (frequency of 300 MHz to 300 GHz). Widely used for wireless communications by smartphones, Wi-Fi, and other devices as well as for television broadcasts, radar, and microwave ovens.

Mild Hybrid Electric Vehicle (MHEV)

A type of hybrid vehicle that uses an engine and a 48 V battery (power source) to drive motors. Offers the advantages of reduced CO2 emissions and lower cost compared to a full hybrid vehicle.


An abbreviation of "multi-input" and "multi-output", wireless LAN technologies. In conventional wireless LAN systems, radio waves disturbed due to the diffused reflection of obstacles may cause reduced transmission speed. A MIMO receives radio waves of diffused reflection and restores the original data signals using two or more antennas on the transmitting/receiving side concurrently, therefore attaining data transmission with high-speed and hi-reliability without extending the frequency band.

Mini PCI

A standard for small expansion cards using a PCI bus that is the bus (data transmission path) standard used inside personal computers.

MLCC (Multilayer Ceramic Chip Capacitor)

A chip capacitor for SMD (surface mount device) without lead wire, manufactured by thin-film multilayer method. Today's mainstream of the production method is the sheet method used to manufacture by arraying multiple layers of a conductive paste made of a thin dielectric sheet and an electrode by turns, and cutting them, then firing.

MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor)

A type of field-effect transistor (FET). Commonly used as general ICs and LSI.


An in-vehicle information communications LAN standard used with car navigation systems, AV systems, and other equipment.

Motion Sensor

A sensor that detects the motion, pose, position, and other attributes of an object in three dimensions. They are compound sensors that combine three-axis acceleration sensors with angular velocity sensors, magnetic sensors (compasses), barometric pressure sensors, and other components. Used in game devices, drones, robots, car navigation systems, and other applications.

MPU (Micro Processing Unit)

Also called a processor or microprocessor. A semiconductor device that integrates a central processing unit (CPU) with memory and other components. Generally, refers to a component with greater functionality than a microcontroller unit (MCU).

MR Head

A magnetic head that uses magnetic resistance (MR) effects. Used as HDD heads until the development of GMR heads.

MRAM (Magnetoresistive Random Access Memory)

A random access memory chip using a magnetic element which uses the Spintronics technology. Using a tunnel magnetoresistance effect (TMR) that is the principle of the TMR element of heads for HDD. Attaining high-speed reading/writing with low power consumption, and expected to be the next-generation non-volatile/mass memory chip.

Multilayer Capacitor with Leads

A radial lead capacitor on which two leads are soldered to the external terminal of a multilayer ceramic chip capacitor (MLCC) and coated with resin. Since the lead wire alleviates mechanical and thermal stress, these capacitors are used in parts exposed to vibration and shock such as motors.


NAND Type Flash Memory

A flash memory is a non-volatile storage element which retains data even if the power is turned off. NAND type flash memory is suitable for mass data storage, has attained rapid growth since about 2003, and has come to be widely used as a memory card in various mobile devices such as digital still cameras, smartphones, and portable music players, as well as for USB memories and SSDs.

NAND Type Flash Memory Controller LSI

A controller LSI that controls a NAND type flash memory.

Nasiri Process

A type of wafer level packaging (WLP) for MEMS devices. A unique method in which the IC wafer on which circuits are form is covered with a MEMS wafer so that it is sealed and electrically joined. Patented technology of InvenSense Inc., a member of the TDK Group.


Neodymium Magnet

A magnet made from neodymium, iron, and boron. A rare earth magnet with maximum magnetic power.


TDK's brand name for a neodymium magnet that is the most powerful rare earth permanent magnet. Plays an important role in extensive fields including VCM (voice coil motor) to drive heads for HDD, drive motors in EV (electric vehicle) or HEV (hybrid car), and actuators in OA and AV equipment.

NFC (Near Field Communication)

An international standard for near field communication systems with a communications range of about 10 cm. Unlike Bluetooth, Wi-Fi, and other standards, no complicated settings are required, and pairing (connection settings) and transfer of photos and videos are possible with one touch. In addition, since electronic payments can be made easily simply by holding a smartphone over devices, it is being installed in smartphones and uses are expanding. IC cards, such as Suica and PASMO public transportation cards, and Felica, which is used for electronic payments, are types of NFC (Type F).


Noise in electronic devices includes conduction noise transmitted through source lines or signal lines and radiation noise that radiates from equipment or invades into equipment as electromagnetic waves. Conduction noise includes two types; differential mode (normal mode) and common mode. Common mode noise is becoming especially problematic with the increase in digital equipment and high-frequency, and its importance is increasing.

Noise Countermeasure Component

Noise Suppression Filter

An EMC countermeasure component that utilizes the property of ferrite of absorbing noise and converting it to heat. Compared to chip beads, low-loss noise elimination characteristics can be achieved in higher frequency bands.

Noise Suppression Sheet

A magnetic shielding material made from a magnetic material and resin. Noise suppression sheets control unwanted electromagnetic waves and noise radiated from electronic components over a wide range of frequencies. TDK offers noise suppression sheets under the product name Flexield.

Non-Insulated DC-DC Converter

A compact DC-DC converter such as a chopper power supply in which the primary and secondary sides are not electrically insulated. Used as POL converters for driving ICs and other components and for other applications.

Non-Lead Piezoelectric Ceramics

Non-Magnetic Material Core

A ferrite core is used to raise the inductance of a coil, but high-frequency range loss becomes large. For this reason, a glass-ceramic group non-magnetic material core is used in inductors for high-frequency requiring low loss and high Q characteristics.

Non-Volatile Memory

Memory that records data and maintains it even when the power is turned off. Includes flash memory, MRAM, hard disk drives, and magnetic tape.

Notch Filter

A filter that impedes only a specific, narrow frequency band. Also called band stop filter.

NTC Thermistor

A thermistor with a negative temperature coefficient (NTC), meaning that its resistance decreases with a temperature rise. Also simply called a thermistor. An element incorporating semiconductive ceramics, used in temperature sensors, thermometers or circuit protection elements.


OIS (Optical Image Stabilizer)

A camera shake correction mechanism used on digital cameras, video cameras, smartphones, and other devices.

OP Magnet

The world’s first ferrite magnet. Invented by Dr. Yogoro Kato and Dr. Takeshi Takei of the Tokyo Institute of technology in 1932.

Optical Communication Component/Module

Components and devices used in connections, branches, amplifiers, and other parts of systems and communications networks that use laser light such as optical connectors, optical splitters, optical isolators, optical pickups, optical demultiplexers, and optical modulators.

Optical Pickup

An optical pickup is one reads/writes signals by irradiating laser beams to a signal surface in CDs, DVDs, etc. Consists of a semiconductor laser (LD), a light-emitting device, a lens, a beam splitter, etc.

Oscillator Circuit

A circuit that outputs a continuous electrical vibration (alternating current signal). Types include LC oscillator circuits that combine an inductor (L) and capacitor (C) and crystal oscillator circuits that use crystal oscillators.

Parallel Transmission

A system that collects and transmits data of 16-bits, 32-bits, and so on, using two or more signal lines while carrying out synchronization. More efficient than a serial transmission using one signal line, but a gap arises at the data arrival time of each signal line along with high-speed. For this reason, a differential transmission system using two signal lines is adopted in high-speed digital interfaces such as USB and IEEE1394.

Passive Matrix System/Active Matrix System

A drive system used to illuminate an organic EL element. A passive matrix system is one that constitutes the electrode lines of a lengthwise direction and a longitudinal direction like a network and drives a pixel in every line. On the other hand, an active matrix is driven by a TFT (thin-film transistor) installed in each pixel.

Patch Antenna

Another term used for a micro strip antenna. A small and flat antenna made by etching metal on a substrate. Used in high-frequency devices with more than microwave, such as Wireless LAN etc.

PCB (Printed Circuit Board)

A printed board or printed circuit board for mounting electronic components.

Permanent Magnet


Ease of absorption of a magnetic flux (line of magnetic force) in magnetic materials. A magnetic material with high magnetic permeability absorbs a magnetic flux efficiently like a sponge absorbing water. Expressed by the symbol µ; a high µ material of ferrite indicates that it has high magnetic permeability.

PFC Circuit


Plug-in hybrid vehicle. A type of hybrid vehicle with an in-vehicle battery that can be charged by plugging it into a commercial alternating outlet.

Photo Lithography

A technology that exposes and imprints detailed patterns of circuits on a substrate with an application of photographic technology in manufacturing of semiconductor integrated circuits or HDD heads. A related photolithographic device is called a stepper.

Piezoelectric Actuator

A device that uses the piezoelectric effect to convert electrical energy into mechanical energy. Widely used in ink jet printer heads, camera shake correction mechanisms, and other applications.

Piezoelectric Buzzer

A sound generator using piezoelectric ceramics that oscillates due to its distorted outer shape when alternating voltage is applied. Often used as a sound generating component, such as for an alarm sound in electronic equipment. For an electronic buzzer, along with the piezoelectric type an electromagnetic buzzer using a magnet and coil is also used.

Piezoelectric Ceramics

Piezoelectric Ignition Element

An element that generates a spark by voltage through piezoelectric effect. Widely used in gas cigarette lighters and gas ranges.

Piezoelectric Materials

Piezoelectric materials are materials that generate electrical voltage in response to applied mechanical stress (piezoelectric effect) and that change shape when electrical voltage is applied (inverse piezoelectric effect). In addition to crystals such as quartz, certain types of ceramic materials also have these properties and are called piezoelectric ceramics. When alternating current is applied to a piezoelectric material, the material vibrates, and consequently, such materials are used in piezoelectric buzzers and ultrasonic generator oscillators. Also, piezoelectric receivers, haptic devices, ultrasonic humidifying units and ceramic resonators are electronic components that use piezoelectric ceramics.

Piezoelectric Receiver

Also referred to as a piezoelectric speaker. A sound generator that uses the oscillation of a piezoelectric material. Used in receivers of phones and information devices to generate voice, melodies, and alarms. There are also varieties used in smartphones to vibrate the display panel.

Piezoelectric Speaker

A thin speaker that uses a piezoelectric ceramic element as a diaphragm.

Piezoelectric Transformer

A converter that converts alternating voltage of the primary side into the oscillation of a piezoelectric material and returns the oscillation to an electrical signal on the secondary side. Simple structure and suited to small-sizing/thin-shaping. Has the advantage that it does not generate electromagnetic noise even under high frequency.


Electricity that is generated through the piezoelectric effect when voltage is created by an external force.


TDK’s haptic feedback actuators. A virtual tactile sensation created by various vibration patterns using multilayer piezoelectric ceramic elements.


TDK’s thin speakers that use a piezoelectric ceramic element as a diaphragm. Can function as wide range speakers by installing on various items.

Plasma CVD Method

Plastics Magnet

A bonded magnet made by combining powders of neodymium magnets or ferrite magnets with plastics and molding (compressing, extrusion, injection molding, etc.). The magnetism is inferior to that of simple substance magnets, but thin-shaped or complicated-shaped products can be manufactured, as used for small motors.


Devices and software that serve as the foundations for operation of a system. For example, MEMS platforms for MEMS sensor devices and others are developed and provided to many and unspecified customers.


A circular magnetic disk used as the recording media for HDDs.

PMR Head

A recording element for HDD using a perpendicular magnetic recording (PMR) system. Realized remarkable improvement in surface recording density compared with the conventional longitudinal recording mode with magnetic recording horizontally to a recording layer. Uses a special kind of medium with a backing layer of a soft magnetic material for a magnetic recording medium.

PoE (Power over Ethernet) Power Supply

An ethernet method that provides power along with data to the receiving side via a LAN cable.

POL (Point of Load)

Installation of a compact power supply near ICs and LSI to respond to the lower voltage and higher current needs of these components. Power supplies used for this purpose are called POL converters.

Polycrystalline Material

A solid-state material consisting of many fine crystal grain aggregates. A ceramic or a ferrite is a polycrystalline material manufactured by firing powder materials. The boundary of crystal grain is called the grain boundary.

Position Sensor

A sensor that detects the movement, linear position, and angular position of an object in a non-contact manner. Types include optical and magnetic.

Powder Metallurgy

A method of making metal products by inserting metal powder material into a die, compressing it, and sintering it at high temperature. Characterized by the ability to mass produce products with complex shapes that are difficult to make through casting. Used for neodymium magnets and other products.

Power Capacitor

A high-capacity film capacitor used in power generation system, industrial equipment and other high-power electric installation and equipment.

Power Cell

A high-capacity lithium ion battery for a robot, drone and electric motorcycle.

Power Factor/Power Factor Correction Circuit (PFC Circuit)

The power factor is the ratio of electric power that is actually effectively being used to the alternating current power supplied by a power source. It is expressed as a number ranging from 0 (0%) to 1 (100%). A circuit that suppresses harmonics contained in sine waves and brings the power factor close to the value of 1 is called a power factor correction (PFC) circuit. Used in switching power supplies to control noise (to control harmonics) and raise efficiency.

Power Ferrite

Ferrite used as core material in transformers or choke coils of power circuits operating with a large current.

Power Inductor

Power Integrity (PI)

Power supply quality. In addition to signal integrity (SI), a concept and its technology currently emphasized as a countermeasure against EMC.

Power Module

A power supply that integrates a power conversion circuit, peripheral circuits, and other components into a compact unit. AC-DC power modules, DC-DC power modules, and other types are available.

Power Supply Inductor

An inductor designed to be suitable for power circuits and DC-DC converters. The winding type is mainly used due to large current flow. A power supply inductor is now often used to drive an IC, due to the multi-functionalization of electronic devices. Also called as power inductor.

Pressure Sensor

A sensor that measures the pressure acting between substances (gases, liquids, solids, etc.). Some sensors use piezoelectric materials and others use semiconductors. They can detect pressure, weight, torque, and so on. Sensors that use MEMS technology are called MEMS pressure sensors.

Printed Circuit Board

Also called a PCB or printed wiring board. The board is made of phenol resin, glass epoxy resin, or other insulating material with copper foil wiring on the surface. Boards are used to make electronic circuits by attaching electronic components with solder or other means. There are various types such as multi-layer boards, build-up boards, and flexible boards.

Programmable Power Supply


A communications procedure used when sending and receiving data by computer. Also used with the meaning of various operational or work procedures in fields other than communications.


A method where a prototype is created in advance to verify and confirm functions, operability, design, and so on, efficiently bringing the product to completion.

PTC Thermistor

A thermistor using an element with positive temperature coefficient (PTC) in which the resistance increases with temperature rise. Manufactured using such material as a semiconductive ceramic that has barium titanate as its major component. Makes it possible to set a temperature where resistance changes suddenly according to material composition, widely used as a temperature sensor, a low-temperature heating device and a circuit protection element etc. Ceramic heaters also use PTC thermistors.

Pulse Transformer

A transformer designed to transmit a pulse wave that functions for digital signals. Since a pulse wave, that is a square wave, consists of a fundamental wave and a higher harmonic, that is multiplied by the integral number of the fundamental wave, and requires a pulse transformer with an outstanding transmission characteristic in a wide frequency range, a special ferrite core is used.


An abbreviation of "physical vapor deposition." Used as a method to form a thin-film on a substrate. Ion plating is a type of PVD.


Q Value

A quality factor exhibiting one of the performances of an inductor or a capacitor. For example, in inductors, a lower resistance or a larger inductance has a higher Q value in the frequency. A high Q inductor is required, especially in a high-frequency circuit.


Radial Lead

Radio Wave Absorber

A material such as ferrite and carbon that absorbs electromagnetic energy in radio waves and changes it into heat is called a radio wave absorption material. A radio wave absorber includes base materials such as a styrene foam, a foaming polyethylene, and an inorganic material. Various types are available to meet various requirements and applied frequency. A compound type combining two or more radio wave absorption materials, such as ferrite and carbon, has excellent radio wave absorption features in a wide frequency band, and is used in echoic chambers, etc. Moreover, a ferrite wave absorber sintered in the shape of a tile is attached to surfaces such as building walls for radio disturbance countermeasures and so on. A radio wave absorber panel for ETC is also used in highway tollgates.

Rare Earth

One of 17 elements collectively referred to as rare earths. Magnets made from rare earth elements such as neodymium and samarium are called rare earth magnets. Uncommon metals such as gold, silver, and cobalt are collectively referred to as rare metals.

Rare Earth Magnet

A permanent magnet consisting of compound elements of rare earth group elements, such as samarium and neodymium, and iron group elements such as iron, nickel, and cobalt. Manufactured by molding and sintering powder materials, resulting in the strongest magnetic energy (energy product) in a permanent magnet. Mainly includes a neodymium magnet (neodymium, iron, and boron magnet). Commercially produced by TDK as NEOREC series.


Reflow Soldering

A soldering method used primarily for chip components. First, chip components are tentatively bonded on a printed circuit board using cream solder, and they are heated in a furnace called a reflow furnace, and then the melted solder in the cream solder completes the soldering of components and PC board.

Residual Magnetic Flux Density

After magnetizing a ferromagnetic material such as iron or ferrite to reach its saturation magnetic flux density, even if the current is weakened to return the applying magnetic field to zero, the ferromagnetic material remains magnetized. The flux density, called a residual magnetic flux density, is an index that shows the level of magnetic energy as well as the coercive force in a permanent magnet.


One of the three major passive components, along with the capacitor and the inductor (coil). Resistors used in electronic devices are compatible with surface mount technology (SMT), and the thick-film chip type is mainly used.


An IC is driven by a clock signal (reference signal) with a certain constant frequency. A resonator oscillates this clock signal. A small chip resonator using piezoelectric ceramics is used in digital equipment.


An abbreviation of "radio frequency." Also used to signify "high-frequency" in communication devices.

RF Front End Module

RFID (Radio Frequency Identification)

A system for confirming ID information wirelessly (using radio frequency (RF)). Exchanges signals between an RFID tag (IC tag) with a small IC and a reader/writer device using short range wireless communications. A key feature is that it can process a larger amount of information than bar codes and can write and rewrite information. NFC (near field communication), which is used for electronic payments by smartphones, is also a type of RFID technology.


A ripple-like AC component that flows superimposed on DC current in power supply circuits. Ripple becomes a cause of noise as well as a cause of heat generation in capacitors, and as a result, allowable ripple currents are specified.

RoHS (Restriction of Hazardous Substances) Directive

Restrictions on hazardous substances established by the European Union (EU). The directive is controlling the manufacture and sale in the EU of electrical and electronic equipment, component parts and materials that contain heavy metals including lead, mercury, cadmium, and hexavalent chromium and organic compounds such as polybrominated biphenyls (PBBs), in concentrations exceeding the maximum permissible levels.

Rotation Sensor

A sensor that detects the rotation speed (number) of an engine, motor, or other devices. There are many varieties including optical, electromagnetic pickup, and types using Hall elements and MR elements.

Rubber Magnet

Rubber magnet. A bond magnet made by mixing powders of ferrite magnets and molding into rubber, etc. Can be cut or bent freely for processing.


Samarium-Cobalt Magnet

A type of rare-earth magnet. Magnetic power is slightly less than a neodymium magnet, but samarium-cobalt magnets have excellent corrosion resistance and are characterized by no degradation of characteristics even after processing.


Saturation Magnetic Flux Density

When placing a ferromagnetic material such as iron and ferrite into a coil and enlarging a current sent into a coil, the magnetization intensity of the ferromagnetic material also becomes larger gradually and is finally saturated. The flux density of the ferromagnetic material at this time is called a saturation magnetic flux density. Using a core material with large saturation magnetic flux density in transformers enables reduction of core cross sections or numbers of turns in coils as well as volumes.

SAW Filter

A filter for high-frequency using a surface acoustic wave (SAW) due to the oscillation of a piezoelectric ceramic. Used in televisions, high-frequency circuits of smartphones, etc.

Screen Printing

A printing technique used in the manufacture of multilayer electronic components and other products. A technology for printing using a paste like dielectric, ferrite, metal, or other material as a printing ink applied through a screen mask (mesh) that forms a printing pattern.

Self-Resonance Frequency (SRF)

Since an actual capacitor or inductor has a capacitor component or inductor component, that does not appear in circuit diagrams, it acts the same as an LC oscillator circuit, and its impedance decreases or increases remarkably in a certain frequency in the high-frequency range. This frequency is called a self-resonance frequency (SRF). A capacitor or inductor functions within a range of self-resonance frequency. Therefore, one with a high self-resonance frequency is required in capacitors or inductors used in the high-frequency range.


Scanning electron microscope.


A substance with interim properties of electric conductors, such as silicon, germanium, and selenium, and insulators is called a semiconductor, and active elements such as diodes and transistors using them are called semiconductor devices. An IC or an LSI is one formed of many semiconductor devices on a silicon wafer that is a semiconductor. A semiconductor, such as gallium arsenide or a gallium nitride, consisting of two or more types of elements is called a compound semiconductor.


Serial ATA (SATA)

A standard for connection of an HDD (hard disk drive) and a personal computer. While the conventional ATA uses a parallel system that has a limitation in improvement in transmission speed, the SATA attains improved transmission speed by using a serial transmission system. Since a SATA is a differential transmission system, a common mode filter is used as a countermeasure against noise.

Serial Transmission

A system that sends a signal by bit sequentially through one signal line and a ground. Also, a term for a parallel system that collects and transmits the data of 32-bit or 64-bit through two or more signal lines while synchronizing.


A computer and storage (memory devices) that process and store data via the Internet or other network. A facility where servers are installed and accommodated is called a data center.

SESUB (Semiconductor Embedded in SUBstrate)

A TDK IC embedding substrate technology for embedding thinned IC chips in substrate.

Sheet Method

Methods to manufacture multilayer chip components include the thick-film printing method and the sheet method. The sheet method is one that arrays multiple layers of an electrode and a conductor pattern, etc., on a thin sheet called a green sheet.

Shock Sensor

A sensor that detects mechanical shock or vibration. Generally, acceleration sensors are used.

Signal Integrity (SI)

Signal quality. A new concept applying its technology as a countermeasure against EMC as well as to ensure power integrity (PI = power supply quality).

Silicon Disc

Single Crystal

A solid substance that has the same crystal axis orientation in all parts.


A key component of HDD heads. A large number of HDD head read and write elements are formed on a wafer using thin-film technology. A slider is made by cutting this and forming chips. A slider attached to a suspension (support string) is called an HGA. What is generally called the HDD head is an HGA.

Smart Crystal

A single crystal florescent element jointly developed by TDK and Tohoku University. Unlike the conventional method of processing from bulk single crystals, it is characterized by being able to be manufactured in any shape such as tube, plate, and store-shaped cross sections. It is expected to be used in automobile laser headlamps and other applications.

Smart Grid

The next-generation power grid that efficiently controls power on both the generation/transmission side and the demand side by using information and communications technology (ICT) such as solar power generation, wind power generation, and smart meters.

Smart Meter

A new-generation electric meter which has communication functions using information and communication technology (ICT) and is networked. By digitally measuring the amount of electricity used, it is possible to visualize power consumption by consumers, improve the efficiency of electricity consumption in a region, and achieve various remote services. Important equipment that supports smart grids and HEMS.

Smart Speaker

An interactive speaker that uses voice recognition technology to understand, respond to, and execute spoken commands, instructions, and questions. Also called an AI speaker.


The method used to mount an electronic component on a circuit board is called surface mount technology (SMT), and an electronic component compatible with this is called a surface mount device (SMD). Since most SMDs are small chip types without lead wire, this term means almost same as chip component.

SMT (Surface Mount Technology)

Snubber Capacitor

A capacitor that protects switching elements by absorbing noise generated from switching in switching power supplies and other devices. Film capacitors are primarily used. A type known as the power film capacitor is used in power substation and transmission facilities.

Soft Magnetism


A solenoid coil. A rolled cylindrical coil.

Sound Generator

A sound converter that emits an alarm and a melody. They include a piezoelectric buzzer and a piezoelectric receiver using piezoelectric elements and an electromagnetic buzzer using a magnet.

S Parameter

When an alternating current signal is captured as a wave, the characteristics of high-frequency circuits and high-frequency components are expressed by the degree of reflection and transmission.

Spin Coat

A method used to coat a thin-film by applying a material solution to a rotating substrate at high speed and dispersing the solution by centrifugal force. Used in manufacturing of recording layers of CD-R, for example.


A new field of electronics that makes use of both the charge and spin (a motion similar to rotation) of electrons. GMR heads used in HDDs are a pioneering application of spintronics. Since magnetic information can be converted into electrical signals without using a coil, applications as non-volatile memory such as MRAM are advancing.


A method used to form a thin-film by making a high-speed ion collide with metal and other materials in a low-pressure gas and adhering the released atoms to a substrate. Spatter means "sprinkle." The metal and other materials used to make ion collide is called a sputtering target.

Sputtering Target

SQUID (Superconducting Quantum Interference Device)

An ultra-sensitive magnetic sensor that uses the tunnel effect of quantum mechanics. Used for weak biomagnetism and non-destructive inspection.


SSD (Solid-State Drive)

A storage device that uses NAND flash memory. Since there are no moving mechanisms and access speeds and impact resistance are excellent, the replacement of HDDs with SSDs is progressing in personal computers and other devices.


A photolithography device used in photolithography process in manufacturing of semiconductor integrated circuits or heads for HDD.


A site or device for storing data. Storage includes HDDs, SSDs, USB memory devices, SD cards, optical discs, and magnetic tape. In addition to storage used in PCs, AV devices, and industrial equipment, there is also online storage (cloud storage) that stores data in the cloud via the Internet. Data center servers are connected to high-capacity storage.

Stray Capacitance

A hidden capacitor component in the structure of circuits or electronic components such as a coil, an internal electrode, a terminal electrode, a lead wire, etc. A stray capacitance may affect by building a resonance circuit with the inductance or resistance component of conductors and so on, and therefore desired to be small in the high-frequency range.

Super Capacitor

A TDK electric double layer capacitor (EDLC) packaged in a metal leaf laminated film. Resistance is low and the components are thin and lightweight, making them ideal for use as supplemental power supplies or energy harvesting in mobile devices, storing recovered energy, and other applications.

Super Hi-Vision (SHV)

An ultra-high definition television standard researched and developed mainly by NHK. Horizontal resolution is 7,680 pixels and vertical resolution is 4,320 pixels. Equivalent to 8K TV.

Surface Mount Technology/Surface Mount Device

Surface Potential Sensor

A sensor that controls the electrostatic charge amount precisely by detecting the potential of a photosensitive drum without contact in color copiers or laser beam printers.


Excessive voltage or current that occurs momentarily and enters a device as a result of electrostatic discharge (ESD), switches opening and closing, or an induced surge caused by lightning discharge. To prevent failure and malfunction of devices, circuit protection elements such as varistors and arrestors (surge arrestors) are used.

Switch Catch

Switching Power Supply

A direct current stabilization power supply using a switching operation (ON/OFF operation in transistors). Also called a switching regulator. A device that acquires the output of prescribed stable voltage and current from commercial power supply sources (AC100V/200V) or DC power supply sources. Its size and weight can be reduced since it does not require a heavy and bulky power transformer like its similar device, the linear power supply (series regulator etc.). Moreover, it excels in energy efficiency, widely used as a power supply for various electronic devices such as information devices including OA equipment, FA equipment and personal computers. Includes a forward system and a flyback system according to circuit system, and a unit type, an onboard type, and a module type according to appearance, size, and use. Since a switching power supply generates a high frequency noise called switching noise with the operation of a transistor, it is required to take all possible measures against noise.

System-on-Chip (SoC) / System-in-Package (SiP)

An accumulation of active components such as an IC or passive elements such as a capacitor and an inductor in one chip (SoC), and one grouping every system in one package (SiP), by using a semiconductor manufacturing technology and LTCC technology.


TAMR (Thermal-Assisted Magnetic Recording)

A new technology for raising the recording density of HDDs. A method in which the fine magnets in the recording layer over magnetic disk are spot-heated with laser light only when data is written, making it easy for magnetization to be reversed for magnetic recording. A method that uses microwaves instead of lasers is called microwave assisted magnetic recording (MAMR).

Tangent Delta (tanδ)

Loss factor. The degree of energy loss inside capacitors and inductors, which is prominent in the high frequency range. The smaller the number, the smaller the loss. In the case of a capacitor, it is also called the dielectric tangent, and the reciprocal of the numerical value is the Q value (quality factor).

Tape Feeder System

A system used to take out a chip component held in a carrier tape and automatically mount it using a mounter (chip component mounting equipment).


Transmission Electron Microscope.

Temperature-Responsive Lead Sensor

A temperature sensor with a contact combining a magnet, a temperature-responsive ferrite, and a lead relay. Ferrite loses its ferromagnetic properties at above Curie temperature. A temperature-responsive ferrite is a ferrite with a Curie temperature lowered to close to the normal temperature. The lead relay contact is opened/closed at operating temperature. Widely used in intermittent temperature control in thermal rice cookers, the exterior units of air conditioners, and toilet seats with warm water cleansing function.

TFC/TFCP (Thin-Film Capacitor)

THD (Total Harmonic Distortion)

The ratio of harmonic components (noise components) mixed in with the fundamental wave.


An element that changes its electrical resistance according to temperature. A coined term combining heat (thermal) and resistance (resistor). Includes the NTC thermistor with a negative temperature coefficient (NTC) that decreases its resistance with a temperature rise, and the PTC thermistor with a positive temperature coefficient (PTC) that increases its resistance with a temperature rise. The NTC thermistor is often used as temperature sensor, thermometer or circuit protection element, and generally a thermistor indicates an NTC thermistor. The PTC thermistor is used as circuit protection element or heating element.

Thick-Film Printing Method

Methods for manufacturing multilayer type electronic parts include thick-film printing method and sheet method. The thick-film printing method prints and accumulates a base material and an internal electrode by pasting the materials, such as a ferrite, a dielectric ceramic and a metal conductor, in a similar method to screen printing.

Thick-Film Technology

A term used in contrast to thin-film technology. A layering method for manufacturing multilayer ceramic capacitors, multilayer inductors, and other components.

Thin- Film Common Mode Filter

A common mode filter that is formed by condensing fine thin-film inductors and such on substrates like ferrite, with the application of the thin-film process technology cultivated by manufacturing of heads for HDD. Super-small size with an outstanding noise suppression effect that suppresses the influences on transmission signals thoroughly.

Thin-Film Capacitor (TFC/TFCP)

A capacitor with a structure that sandwiches a thin dielectric film between two thin metal foils that serve as electrodes. Characterized by flexibility and the ability to easily be cut to the necessary shape and size. Excellent decoupling effects are achieved by embedding thin-film capacitors directly under LSI on a substrate.

Thin-Film Thermal Print Head

A thermal recording print head used in commercial label printers, professional-use bar code printers, and other applications.

Three-Terminal Filter

An EMC countermeasure component that internally integrates an inductor and a capacitor. Since it has three terminals—input, output, and ground—it is called a three-terminal filter. Attenuation effects are greater than those of an individual inductor, capacitor, or chip beads, and noise elimination characteristics are excellent. These filters are classified as L type, T type, π type, double-π type, pulse response type, and other types according to the combination of elements. TDK has a lineup with various frequencies and impedance characteristics, as well as array products that integrate multiple three-terminal filters into a single component for significant space-saving effects.

Through Hole

A hole that goes through a printed circuit board whose interior is plated with copper. They are created for inserting electronic components with lead wires and for creating an electrical connection between the front and back surfaces of the printed circuit board. A hole with a diameter smaller than that of a through hole used for conducting electricity is called a via hole.


A quantification of the digital data processing or transfer speed in a computer or on a network. The unit is bps (bits per second).

TMR Head

An HDD head reading element that utilizes the tunnel magnetoresistance (MR) effect. The magnetoresistive factor, which indicates the head’s density, greatly exceeds that of conventional GMR elements, enabling more accurate reading of high-density signals.

TMR Sensor

TMR is an abbreviation for tunnel magnetoresistance (MR) effect. A highly sensitive magnetic sensor that utilizes the tunnel phenomenon of quantum mechanics. Used as an angle sensor, rotation sensor, position sensor, and other sensor types.


The existing magnetic recording of HDD were attained through a procedure that applied a magnetic field to a recording layer on a hard disk, that is a recording medium, from a recording head which magnetized and arrayed mini-magnets on a recording layer horizontally. This is called the longitudinal magnetic recording method. However, because the longitudinal magnetic recording method has density limitations, a perpendicular magnetic recording (PMR) system that arrays mini-magnets perpendicularly on the recording layer was developed. A PMR head is used for this perpendicular magnetic recording. A TMR-PMR head, mainstream as of now, is a combination of a TMR head and a PMR head, that is a reading element with high sensitivity. A perpendicular magnetic recording system is attained by combining the use of a PMR head and a recording medium, using a special recording medium with a backing layer of soft magnetic material.

ToF (Time of Flight)

A distance measurement method called the time-of-flight method. Distance is calculated from the time when light or ultrasonic waves are reflected by an object and returned.

Toner Concentration/Residual Volume Sensor

A sensor used to maintain a proper color reproduction and a stable copy quality in color copiers. A toner concentration sensor functions by a differential transformer system using a highly efficient ferrite core and a residual volume sensor by a piezoelectric oscillating system that detects a residual volume with high precision regardless of particle size and specific gravity of toners.


A doughnut-shaped core or a coil wound around the core.

TPMS (Tire Pressure Monitoring System)

A system that senses the air pressure of automobile tires and wirelessly transmits the data to an in-vehicle receiver to provide notice of any abnormalities.


A device that converts a physical quantity of electric power, vibration, heat, sound waves, light, and so on into an electrical signal. Commonly used with a sensor as a set.


When two coils are wound around a ring shape core and a change occurs in the current sent through one coil of the two, an electromotive force occurs in the other coil through the flux change of a ring shape core. This is called a mutual induction (a type of electromagnetic induction). A transformer is a device that adapts this principle, converts an alternating voltage or an impedance by combining two or more coils with a common magnetic circuit. Various types include inverter transformers, pulse transformers, rotary transformers, and flyback transformers, as well as power transformers, and use ferrite core material according to function in order to reduce transformer loss.

Transformer Loss

The total sum of core loss, that is the loss from a core, and copper loss due to electric coil resistance, as overall loss from the whole transformer.

Transparent Conductive Film

A type of functional film. A material formed by applying a conductive film on the surface of a transparent film using spin coating, sputtering, or other such technique. Used in the electrodes of touch panels and other applications

Transponder Coil

An antenna coil with small size and high sensitivity, used in tire pressure monitoring systems (TPMS) of automobiles, immobilizers, passive keyless entry (PKE), etc.

Tunnel Effect

A quantum mechanical phenomenon where an energy barrier that normally cannot be overcome is penetrated by particles such as electrons with a certain probability. Elements such as HDD TMR heads use the tunnel effect.

TVS Diode

A protective element used to control high transient voltage from surges, static electricity, and so on.



Ultra high definition television.

Ultrasonic Adhesion/Ultrasonic Welding

A method used to melt and join materials using friction and impulsive forces through supersonic oscillation. Applied to IC lead wire bonding, etc.

Ultrasonic Flip Chip Mounter

The mounting method that incorporates an IC on a printed circuit board as a bare chip (where a lead wire is not attached) is called a flip chip system, and a mounting equipment of this flip chip system is called a flip chip bonder. Enables reduction of mounting area and space-saving on a printed circuit board, compared with a wire bonding system.

Ultrasonic Humidifying Unit

One adopting the phenomenon that when placing electrodes on both sides of a piezoelectric ceramic and adding a high-frequency voltage, an oscillation occurs in the thickened direction through a piezoelectric effect. When an oscillator generates an ultrasonic frequency under water, a mist is released from the water surface. Features that the diameter of the mist drop is finer than that of natural mist. Used in medical treatments such as inhalers besides home humidifiers. Also called a nebulizer.

Ultrasonic Sensor

A sensor that detects sound waves higher than the frequencies perceptible to humans (approximately 20 Hz to 20,000 Hz). There are various types including those that use a piezoelectric ceramic oscillation diaphragm and MEMS ultrasonic sensors that have been miniaturized using MEMS technology. By transmitting and receiving ultrasonic waves, they can also be used as short-range sensors and for other applications.


An abbreviation of "Ultra Wide Band." Also called an ultrawideband wireless. A short-distance wireless radio communication system using radio waves of extremely wide band but with weak transmission strength (below the noise from personal computers). UWB is one of high-speed and mass data communication technologies which realizes wireless connection among various digital equipment. However, since UWB communications overlap with the frequency band that other wireless communications use, it is strictly defined to suppress the radio wave intensity in order to avoid interference.


Vapor Deposition

A method used to form a thin-film by heating metal and other materials in a vacuum and adhering the evaporated atoms and molecules to a substrate. Also called a vacuum deposition.

Variable Output Power Supply

A power supply that allows the output voltage and output current to be set to an arbitrary value. Used in testing and research. Also called programmable power supply and constant voltage, constant current (CVCC) power supply.


A term coined from variable resistor that means an element whose resistance value changes with the voltage. An element that exhibits high resistance to a certain voltage, and if that voltage is exceeded, the resistance suddenly reduces, allowing a large current to flow. Used to prevent such incidents as circuit malfunction or destruction of ICs due to a momentary unusually high voltage that enters a circuit caused by lightning or static electricity surge. Consists of a special semiconductive ceramic sandwiched between electrodes. Types include block, strap, disk, and chip varistors. The SMD type chip varistor is small with high withstanding voltage, and demand has increased as a replacement for TVS diodes (Zener diodes) used in the past.


Voltage controlled oscillator. An essential component to precisely control oscillation frequency from a synthesizer (circuit that makes specific frequency) in wireless communication equipment like smartphones, in order to receive radio waves of specific frequency from base stations.


A conduction hole in a printed circuit board used for electrically connecting layers. A drill or laser is used to make a hole, which is then plated with copper. Also called via hole. Those used as heat dissipation routes are referred to as thermal vias.

Volatile Memory

A type of memory that stores data only when power is supplied externally and the recorded data is deleted when the power supply turns off. Types include DRAM.

Voltage Control Oscillator


Virtual reality.


Abbreviation of Vehicle to X (Everything). A fundamental technology of connected cars for wirelessly connecting automobiles with various other things (automobiles, roads, pedestrians, infrastructure, and so on).



IEEE-802.16 standard. A fixed wireless communication protocol that covers a wide area of approx. 50km in radius with a single antenna (transmission speed is a maximum of 70 Mbps). Called a wireless MAN (Wireless Metropolitan Area Network) in comparison to a wireless LAN used indoors. Assumed to be used in the last one mile where broadband services are not available, such as on mountain slopes and in depopulated districts.

Wire Bonding

A method of bonding the terminals (pads) on the surface of an IC or LSI bare chip (die) to terminals on a circuit board using fine wire made of metal or other material. The device that performs this is called a bonding machine, and ultrasonic vibration or other means are used for bonding.

Wireless LAN

Also called Wi-Fi. A wireless LAN that uses wireless communications to enable PCs and peripheral devices to be used in relatively small areas such as homes, offices, stores, schools, and public institutions without the need for cable connections. Radio wave used are 2.4 GHz and 5 GHz. The official standard name is IEEE 802.11, and standards in the name of formulation are 11b, 11a, 11g, 11n, 11ac, and 11ax. 11ac is also called WiFi5, and 11ax is called WiFi6.

Wireless Power Transfer

Non-contact power supply. A system that uses electromagnetic induction and magnetic resonance to transmit electric power without contact. Used to charge batteries in mobile devices, automated guided vehicles (AGVs), xEVs, etc. devices.

WLP (Wafer Level Package)

For semiconductor devices and MEMS devices, a large number of elements are formed and sealed on a wafer, and then chips are formed by dicing. Also called the WLCSP (Wafer Level Chip Size Package), since the package and chip size are the same.



An airplane pilot operates engine throttle and wing flaps by controlling an actuator according to electrical signals through electrical wiring from the cockpit. This is called "fly-by-wire." Also in the automotive field, brakes or steering, conventionally controlled by oil pressure have been changed to an electrically-driven type, known as "X-by-wire."


A high-speed digital data communication technology that uses twisted-pair metal wires as the communications lines. Types include ADSL and VDSL, and they are collectively referred to as xDSL. The main type of broadband until the spread of optical communication (FTTH).

X8R-type Multilayer Ceramic Chip Capacitor

The permissive variation in capacitance in multilayer ceramic chip capacitors is determined by use temperature range. X8R has a strict standard that capacitance cannot vary by more than ±15% over a temperature range of -55 to +150°C. This meets the high temperature environment of the engine compartment of automobiles.


A general term for electric vehicles including battery electric vehicles (BEV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and fuel FCEV (Fuel Cell Electric Vehicle).

xEV DC-DC Converter

An in-vehicle power supply that converts the high voltage of the xEV main battery (generally 300 V to 400 V) into low voltage (such as 12 V) used to operate the various in-vehicle electrical equipment.


Zener Diode

Also called a rated voltage diode. General diodes are used in rectifier circuits because they allow current to flow in the forward direction smoothly and almost no current to flow in the reverse direction. When voltage is applied in the opposite direction, a Zener diode does not pass current up to a certain voltage (the Zener voltage), and when that voltage is exceeded, current flows through rapidly. Zener diodes use this property and are used as circuit protection elements that supply a constant-voltage current to the circuit and bypass the current when overvoltage is applied. Those used for surge and electrostatic discharge (ESD) countermeasures are also called TVS diodes.


µ (Micro) POL

An ultra-compact DC-DC converter with chip components, such as power inductors and capacitors, mounted on a SESUB board (TDK’s proprietary board with embedded ICs). Used as a POL converter in the final stage of a distributed power supply system.

µ (Mu)