Through Hole Inductors, Toroidal Choke Coils, EMI Line Filters

Power Wirewound Fixed Inductors

Inductor through hole type and description
1(TCRCS) EMI Line Filters
Power choke inductors (TCRCS) are optimized for removing high-frequency noise in power supply. Prepareing small types for mobile devices and higher-power types, customer can select the most suitable product with the appropriate inductance and rated current.
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2(TCDY) EMI Line Filters
The Nickel Core Integrated Inductor (TCDY) measure high current rating up to DC 40 Amp., frequency high up to 1.0MHz with low DC resistance. Three compact sizes are available, 8.2mm x 8.2mm, 10.2mm x 10.2mm, 和 12.5mm x 12.5mm.
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3(TCDU) EMI Line Filters
An integrated circuit structure is provided with (TCDU) inductor formed of a high magnetic susceptibility nickel metal core coil. The Nickel Core Integrated Inductor (TCDU) measure high current rating up to DC 33 Amp., frequency high up to 1.0MHz with low DC resistance.
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4(TCUU) EMI Line Filters
The (TCUU) series is designed to reduce stray capacity between windings by using a single-layer coil and two sections bobbin construction on high permeability ferrite core, which offer excellent high frequency characteristics.
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5(TCAL) Fixed Inductors
Token highly efficient automated production processes offer a full range of high-quality inductors products suitable for automatic plug-in operation. The (TCAL) provides 0204,0307,0410, and 0510 size varieties of different forming, such as Normal & Short Form, F Forming, U Forming, Pana Forming, and bulk products to meet the needs of a variety of manufacturing methods.
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6(TCDA) Large Current Power Inductors
Technology of Diagonal Through Hole High Current Power Inductors (TCDA) Design. Token's TCDA Large Current Series power inductors feature with high current, low DC resistance, high frequency, easy heat dissipation, and high reliability advantages.
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7(TCRB) Radial Choke Coils
Radial High Rated Current Chokes with open magnetic circuit construction design makes better TCR. Token TCRB series structure with open magnetic circuit construction design and protect by UL or PVC Heat-shrinkable tube.
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8(TCRC) Radial Choke Inductors
Power Choke Coil Inductors limit the alternating current through the chokes. The power choke (TCRC) is idael for notebook computers, inkjet printers, photocopying machines, display monitors, mobile phones, broadband modems.
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9(TCRS) Radial Choke Shielded Inductors
Radial choke coil shielded construction design for higher frequency. The TCRS is idael for notebook computers, inkjet printers, photocopying machines, color TV, VCR, camera, microwave ovens, display monitors, mobile phones, broadband modems.
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10(TC1213) Power Wirewound Inductors
Token Develops High-Efficiency Coiled Power Inductors with Large Current and Low DCR. Token has announced a wire-wound power inductor designed for use in the Mother Board of PC and Notebook and various other power devices. The TC1213, measures only 14.0 x 14.5 mm, with a maximum height of 9.5 mm.
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11(TCAC) Air Core Coils, Spring Inductors
Token will do any custom coil windings of Air Coils (Spring Coils) for you. Token manufactures all types of air coil inductors. Air Core Coils' another name is Spring Coils. Token's Air Core Coil (TCAC) Series has advantages of free from iron losses, non-linearity, single layer coils structure, low self-capacitance, and self-resonant frequency.
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12(TCTC) Vertical base mounted Toroidal
Low Loss Powdered Iron Cores, Low EMI, High Current Toroidal Inductors. Token's (TCTC) high current Toroidal Series manufactured by Low loss powdered iron cores offer the smallest size by volume and weight, and lower electromagnetic interference (EMI). Token toroidal can have higher Q factors and higher inductance than similarly constructed solenoid coils.
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13(TCFB) Inductor Ferrite Beads
Ferrite bead is a kind of anti-jamming applications the fastest growing components, cheap, easy to use, filtering high-frequency noise were improved significantly. Ferrite beads commonly used in filtering and electromagnetic noise reduction, Token's Ferrite Beads TCFB series manufactured by using iron, nickel, zinc oxide mixture made with high resistivity and high magnetic permeability.
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14(TCWB) Wide Band Chokes
Excellent EMI Suppression Capability Wide Band Choke Coils (Inductor Filter). Token's TCWB series use of insulation between the coil core winding method. To ensure that the transient over-voltage under the action of short circuit breakdown does not occur. And when the instantaneous high currents flowing through the coil, the core is not saturated.
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15Through Hole Chokes and Inductors (TCPC)
The TCPC features with small size, high Q value, low cost, high self-resonance frequency, high availability of a large induced current, small magnetic flux leakage.

Magnetic Product Terminology & Glossary

Air Core Inductor (Ceramic Core Inductor)

Air core inductors are often referred to as "Ceramic Core" inductors. Air core inductor is most often used in high frequency applications where low inductance values, very low core losses and high Q values are required.

Ceramic has no magnetic properties. Thus, there is no increase in permeability due to the core material. Its main purpose is to provide a form for the coil. In some designs it also provides the structure to hold the terminals in place. Ceramic has a very low thermal coefficient of expansion. This allows for relatively high inductance stability over the operating temperature ranges.

Axial Inductor

An inductor constructed on a core with concentric leads on opposite ends of the core. Axial inductors are available for both power applications and RF applications, and are available in many core materials including the basic phenolic, ferrite and powdered iron types. Both rod and bobbin shapes are utilized. Axial inductors are very suitable for tape and reel packaging for auto placement.

Inductance & Tolerance

The property of a circuit element which tends to oppose any change in the current flowing through it. The inductance for a given inductor is influenced by the core material, core shape and size, the turns count and the shape of the coil. Inductors most often have their inductances expressed in microhenries (μH).

Tolerance Letter of Inductance Table
Letter Tolerance Inductance
F ± 1 % 1 henry (H) = 106 μH

1 millihenry (mH) = 103 μH

1 microhenry (μH) = 1 μH

1 nanohenry (nH) = 10-3 μH
G ± 2 %
H ± 3 %
J ± 5 %
K ± 10 %
L ± 15 %
M ± 20 %

What is Inductor?

A passive component designed to resist changes in current. Inductors are often referred to as "AC Resistors". The ability to resist changes in current and the ability to store energy in its magnetic field, account for the bulk of the useful properties of inductors. Current passing through an inductor will produce a magnetic field.

A changing magnetic field induces a voltage which opposes the field-producing current. This property of impeding changes of current is known as inductance. The voltage induced across an inductor by a change of current is defined as:
Equation V = L di/dt where V (Induced Voltage); L (Inductance Value).
Thus, the induced voltage is proportional to the inductance value and the rate of current change.

DCR (DC Resistance)

The resistance of the inductor winding measured with no alternating current. The DCR is most often minimized in the design of an inductor. The unit of measure is ohms, and it is usually specified as a maximum rating.


EMI is an acronym for Electromagnetic Interference. It is unwanted electrical energy in any form. EMI is often used interchangeably with "Noise".

Ferrite Core

Ferrite is a magnetic material which consists of a mixed oxide of iron and other elements that are made to have a crystalline molecular structure. The general composition of ferrites is xxFe2O4 where xx represents one or several metals. The most popular metal combinations are manganese and zinc (MnZn) and nickel and zinc (NiZn). These metals can be easily magnetized.

RF Choke

Another name for a radio frequency inductor which is intended to filter or choke out signals.


The impedance of an inductor is the total resistance to the flow of current, including the AC and DC component. The DC component of the impedance is simply the DC resistance of the winding. The AC component of the impedance includes the inductor reactance. The following formula calculates the inductive reactance of an ideal inductor (i.e., one with no losses) to a sinusoidal AC signal.
Equation Z = XL = 2ΠƒL.
This equation indicates that higher impedance levels are achieved by higher inductance values or at higher frequencies.

Matched Impedance

The condition that exists when two coupled circuits are adjusted so that the output impedance of one circuit equals the input impedance of the other circuit connected to the first. There is a minimum power loss between two circuits when their connecting impedances are equal.

Multilayer Inductor

An inductor constructed by layering the coil between layers of core material. The coil typically consists of a bare metal material (no insulation). This technology is sometimes referred to as "non-wirewound". The inductance value can be made larger by adding additional layers for a given spiral pattern.

Quality Factor Q

The Q value of an inductor is a measure of the relative losses in an inductor. The Q is also known as the "quality factor" and is technically defined as the ratio of inductive reactance to effective resistance and is represented by:
Equation Q = XL / Re = 2πƒL / Re
Since XL and Re are functions of frequency, the test frequency must be given when specifying Q. XL typically increases with frequency at a faster rate than Re at lower frequencies, and vice versa at higher frequencies. This results in a bell shaped curve for Q vs frequency. Re is mainly comprised of the DC resistance of the wire, the core losses and skin effect of the wire. Based on the above formula, it can be shown that the Q is zero at the self resonant frequency since the inductance is zero at this point.

Rated Current

The level of continuous DC current that can be passed through the inductor. This DC current level is based on a maximum temperature rise of the inductor at the maximum rated ambient temperature. The rated current is related to the inductor's ability to minimize the power losses in the winding by having a low DC resistance. It is also related to the inductor's ability to dissipate this power lost in the windings. Thus, the rated current can be increased by reducing the DC resistance or increasing the inductor size. For low frequency current waveforms, the RMS current can be substituted for the DC rated current. The rated current is not related to the magnetic properties of the inductor.

Saturation Current

The DC bias current flowing through the inductor which causes the inductance to drop by a specified amount from the initial zero DC bias inductance value. Common specified inductance drop percentages include 10 % and 20 %. It is useful to use the 10 % inductance drop value for ferrite cores and 20 % for powdered iron cores in energy storage applications.

The cause of the inductance to drop due to the DC bias current is related to the magnetic properties of the core. The core, and some of the space around the core, can only store a given amount of magnetic flux density. Beyond the maximum flux density point, the permeability of the core is reduced. Thus, the inductance is caused to drop. Core saturation does not apply to “air-core” inductors.

Self-Resonant Frequency (SRF)

The frequency at which the inductor's distributed capacitance resonates with the inductance. It is at this frequency that the inductance is equal to the capacitance and they cancel each other. The inductor will act purely resistive with a high impedance at the SRF point.

The distributed capacitance is caused by the turns of wire layered on top of each other and around the core. This capacitance is in parallel to the inductance. At frequencies above the SRF, the capacitive reactance of the parallel combination will become the dominant component.

Also, the Q of the inductor is equal to zero at the SRF point since the inductive reactance is zero. The SRF is specified in MHz and is listed as a minimum value on product data sheets.

Shielded Inductor

An inductor designed for its core to contain a majority of its magnetic field. Some inductor designs are self shielding. Examples of these are magnetic core shapes which include toroids, pot cores and E-cores. Magnetic core shapes such as slug cores and bobbins require the application of a magnetic sleeve or similar method to yield a shielded inductor.

It should be noted that magnetic shielding is a matter of degree. A certain percentage of the magnetic field will escape the core material. This is even applicable for toroidal cores as lower core permeabilities will have higher fringing fields than will high permeability toroidal cores.

Toroidal Inductor

An inductor constructed by placing a winding(s) on a core that has a donut shaped surface. Toroidal cores are available in many magnetic core materials within the four basic types: Ferrite, Powdered Iron, Alloy and High Flux, and Tape Wound. Characteristics of toroidal inductors include: self shielding (closed magnetic path), efficient energy transfer, high coupling between windings, and early saturation.

PDF Catalogue

Download Fixed Inductor Terminology & Glossary in PDF file.

Measurements of Fixed Inductors


The inductance is measured with a Q-meter, LCR meter or animpedance analyzer. Fixed inductors for signals: Use of a Q-meter in which the frequency is for direct readout of the inductance or at the specified frequency. Inductors for high current power line circuits: 1kHz or 100kHz.

Q Factor

The unloaded Q is measured with a Q-meter, LCR meter orimpedance analyzer. The frequency of measurement is that at which the inductance hasbeen measured or at a different frequency as specified. However, for high current power line inductors, the resistance is measured andthe Q may be neglected.

DCR (DC Resistance), SRF (Self-Resonant Frequency)

DCR: A digital multimeter is used for measurement;
SRF: Measured with a Q-meter, impedance analyzer or network analyzer.

Dielectric Strength

For specimen coil, apply 100V DC for 5 seconds between the shielding case and terminals. There should be no damage orabnormalities in the inductor.

Shock Tests

The change in inductance, if any, is measured after the following tests.

  • Free Fall Drop Test:
    A specimen coil is mounted on a test board and dropped freely 3 times from a height of 1 meter.
  • Impact Tester:
    A specimen inductor is mounted on a test board and dropped 3 times in three directions with shock applied for 0.01 seconds at 981 m/s2.

The change in inductance, if any, is measured after the tests.

Maximum Allowable Current

The maximum allowable current is a DC Current which causes initialinductance to decrease by 10% or 30%. Or coil temperature to rise by 20°C or 40°C, whichever is smaller. (Reference ambient temperature: 20°C)


After immersion of terminals in flux for 5 to 10 seconds, dip theterminals in the solder bath at 245±5°C for 2±0.5 seconds. Make certain that more than 3/4 of the surface of the terminals are coatedwith new solder.

Dry Heat Test

The change in inductance, if any, is measured after exposure to 85±2°C in a test chamber for 500±12 hours and for 1 to 2 hours at room temperature.

Vibration Test

The change in inductance, if any, is measured after the following condition:

  • A specimen coil/inductor is mounted on a test board of vibration instrument.
  • Overall amplitude: 1.5mm, frequency range: 10~55Hz, and swept in the (10~55~10)Hz order per minute for 2 hrs in each of the 3 directions for total of 6 hrs.

Humidity Test

The change in inductance, if any, is measured after exposure in a test chamber to humidity of 90% to 95% R.H. at 60±2°C for 500±12 hours and 1 hour exposure at room temperature.

PDF Catalogue

Download Measurements of Fixed Inductors in PDF file.

Through Hole Fixed Inductors - General Information

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