Question 1

Why are common mode filters / chokes necessary?

Accepted Answer

﻿	Q.Why are common mode filters / chokes necessary?EMC Components > EMC Components > Common Mode Filters / ChokesA.Common mode filters (common mode chokes) are used for noise suppression of differential transmission and power lines.Filters and chokes are effective for suppression of radiation noise from electronic devices and cables&#44 and for self-poisoning countermeasures (improved reception sensitivity) and noise immunity inside of wireless devices.TDK’s common mode filters and chokes come in a diverse lineup for each type of usage. TDK has prepared a selection guide that makes it easy to check representative products.	Product PortalCommon Mode Filters / Chokes product information	Selection GuideCommercial GradeSignal Line Common Mode Filters/Chokes  Selection GuideAutomotive GradeSignal Line Common Mode Filters/Chokes  Selection GuideAutomotive GradeCommon Mode Filters/Chokes for Power Supply LinesContact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 2

In which locations can common mode filters (common mode chokes) be effectively used as EMC countermeasure components?

Accepted Answer

﻿	Q.In which locations can common mode filters (common mode chokes) be effectively used as EMC countermeasure components?EMC Components > EMC Components > Common Mode Filters / ChokesA.It is recommended that common mode filters (common mode chokes) be mounted close to the connectors of the differential transmission signal or DC power supply lines (inlet/outlet).TDK has published the “TDK EMC Technology—EMC Design Guidebook” as reference material.    			product portal		Common Mode Filters / Chokes					TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		TDK EMC TECHNOLOGYTDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 3

It seems that there is no mark indicating the winding direction (polarity) on common mode filters / chokes. If their directions are different when they are mounted&#44 would the properties change?

Accepted Answer

﻿	Q.It seems that there is no mark indicating the winding direction (polarity) on common mode filters / chokes. If their directions are different when they are mounted&#44 would the properties change?EMC Components > EMC Components > Common Mode Filters / ChokesA.Generally speaking&#44 there is no difference in characteristics in the mounting direction of common mode filers and common mode chokes.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 4

Are there any problems in mounting common mode filters / chokes in GND-signal lines?

Accepted Answer

﻿	Q.Are there any problems in mounting common mode filters / chokes in GND-signal lines?EMC Components > EMC Components > Common Mode Filters / ChokesA.There is no problem when mounting common mode filters or common mode chokes between the GND (ground) and signal line.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 5

Can common mode filters / chokes be used on the primary side of a power supply? Can common mode filters / chokes be used in AC lines?

Accepted Answer

﻿	Q.Can common mode filters / chokes be used on the primary side of a power supply? Can common mode filters / chokes be used in AC lines?EMC Components > EMC Components > Common Mode Filters / ChokesA.Common mode filters (common mode chokes) cannot be used for the primary side of a power supply or for an AC line. Please use a signal line or DC power source line.Please refer to the Selection Guide published by TDK in order to confirm products based on the usage method.			product portal		Common Mode Filters / Chokes					Selection Guides		Commercial GradeSignal Line Common Mode Filters/Chokes					Selection Guides		Automotive GradeSignal Line Common Mode Filters/Chokes					Selection Guides		Automotive GradeCommon Mode Filters/Chokes for Power Supply Lines		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 6

Are there any problems in mounting common mode filters / chokes for signal lines?

Accepted Answer

﻿	Q.Are there any problems in mounting common mode filters / chokes for signal lines?EMC Components > EMC Components > Common Mode Filters / ChokesA.There is no problem using common mode filters (common mode chokes) for power sources in signal lines.However&#44 if you wish to use common mode filters or chokes for signal lines in a DC line (not recommended)&#44 please pay attention to the rated current&#44 etc.Please refer to the Selection Guide published by TDK in order to confirm products based on the usage method.			product portal		Common Mode Filters / Chokes					Selection Guides		Commercial GradeSignal Line Common Mode Filters/Chokes					Selection Guides		Automotive GradeSignal Line Common Mode Filters/Chokes					Selection Guides		Automotive GradeCommon Mode Filters/Chokes for Power Supply Lines		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 7

Do common mode filters / chokes generate heat?

Accepted Answer

﻿	Q.Do common mode filters / chokes generate heat?EMC Components > EMC Components > Common Mode Filters / ChokesA.They generate heat in accordance with the value of [(current value)2 x power consumption of the DC resistance of the common mode filter / choke] for a DC current.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 8

Where can the reflow conditions of TDK’s common mode filters (common mode chokes) be confirmed?

Accepted Answer

﻿	Q.Where can the reflow conditions of TDK’s common mode filters (common mode chokes) be confirmed?EMC Components > EMC Components > Common Mode Filters / ChokesA.For most of our products&#44 the reflow conditions are described in the product catalogs. If there is no description of the reflow conditions&#44 or if you would like to know the number of times of reflow&#44 please specify the relevant product and contact us through one of our sales representatives or distributors&#44 or this website. Example: MCZ1210DH type    			product portal		Common Mode Filters / Chokes						Catalog		Common Mode Filters / Chokes Catalog			Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 9

What is the difference between common mode and differential mode?

Accepted Answer

﻿ Q.What is the difference between common mode and differential mode?EMC Components >  EMC Components >  Common Mode Filters / ChokesA. The common mode refers to signals or noise that flow in the same direction in a pair of lines.The differential (normal) mode refers to signals or noise that flow in opposite directions in a pair of lines.As an example for convenience&#44 consider a configuration where two copper wires are wound around a ring-shaped ferrite core. In this structure&#44 two patterns may exist: one where the currents in the wires flow in the same direction&#44 and another where they flow in opposite directions. These two patterns are “common mode” and “differential mode”.product portal							Common Mode Filters / Chokes		TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC							TDK EMC TECHNOLOGY		TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information	  Inquiries on products&#44 sales&#44 or technical matters

Question 10

What is differential insertion loss?

Accepted Answer

﻿	Q.What is differential insertion loss?EMC Components > EMC Components > Common Mode Filters / ChokesA.This refers to insertion loss of signals transmitted in the differential mode.			product portal		Common Mode Filters / Chokes					TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		TDK EMC TECHNOLOGYTDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 11

What is common mode attenuation?

Accepted Answer

﻿	Q.What is common mode attenuation?EMC Components > EMC Components > Common Mode Filters / ChokesA.This refers to the value that attenuates common mode signals that are mostly noise components.			product portal		Common Mode Filters / Chokes					TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		TDK EMC TECHNOLOGYTDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 12

What is Scd21?

Accepted Answer

﻿	Q.What is Scd21?EMC Components > EMC Components > Common Mode Filters / ChokesA.This expresses the amount of differential signals converted into common mode signals when passing through a common mode filter / choke.			product portal		Common Mode Filters / Chokes					TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		TDK EMC TECHNOLOGYTDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 13

Can common impedance be considered impedance that affects only AC (resonant signals)?

Accepted Answer

﻿	Q.Can common impedance be considered impedance that affects only AC (resonant signals)?EMC Components > EMC Components > Common Mode Filters / ChokesA.Common mode impedance depends on the frequency; therefore&#44 it works against AC. Since DC has a frequency of 0Hz&#44 it is affected by the DC resistance of the product.			product portal		Common Mode Filters / Chokes					TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		TDK EMC TECHNOLOGYTDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 14

Is it okay to use a common mode filter / choke if a current larger than its rated current is applied momentarily?

Accepted Answer

﻿	Q.Is it okay to use a common mode filter / choke if a current larger than its rated current is applied momentarily? EMC Components > EMC Components > Common Mode Filters / ChokesA.Although it depends on the size of the current and the period in which the current is applied&#44 our products are not covered by the warranty when they are used under a current larger than their rated current.			product portal		Common Mode Filters / Chokes					TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		TDK EMC TECHNOLOGYTDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 15

What is the difference between common mode impedance&#44 differential mode impedance and characteristic impedance?

Accepted Answer

﻿	Q.What is the difference between common mode impedance&#44 differential mode impedance and characteristic impedance?EMC Components > EMC Components > Common Mode Filters / ChokesA.Common mode impedance: refers to a characteristic in response to common mode signals (noise). Differential mode impedance: refers to a characteristic in response to leakage inductance. Characteristic impedance: refers to the line impedance when two lines of a common mode filter / choke are considered as a differential transmission line. It has no correlation with the common mode impedance. It is determined by the balance between the leakage impedance and the line capacity.			product portal		Common Mode Filters / Chokes					TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		TDK EMC TECHNOLOGYTDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 16

What is the cutoff frequency?

Accepted Answer

﻿	Q.What is the cutoff frequency?EMC Components > EMC Components > Common Mode Filters / ChokesA.This refers to the frequency at which the signal is attenuated by -3dB in a differential signal.			product portal		Common Mode Filters / Chokes					TDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		TDK EMC TECHNOLOGYTDK EMC TECHNOLOGY--GUIDE BOOK FOR EMC		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 17

Where can I see the RoHS certificate or REACH certificate?

Accepted Answer

﻿	Q.Where can I see the RoHS certificate or REACH certificate?EMC Components > EMC Components > Common Mode Filters / ChokesA.You can view them on the product catalog page. For products for which no certificate is available&#44 please contact a TDK sales representative&#44 the place from which you purchased the products&#44 or distributors.     			product portal		Common Mode Filters / Chokes						Catalog		Common Mode Filters / Chokes Catalog		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 18

In there any display on the product model no. that provides information such as whether the product is lead-free?

Accepted Answer

﻿	Q.In there any display on the product model no. that provides information such as whether the product is lead-free?EMC Components > EMC Components > Common Mode Filters / ChokesA.The product model number of common mode filters (common mode chokes) does not include letters indicating whether the product is lead-free.For information on the environmental-friendliness of the product&#44 please refer to the product catalog or product details page.You can check the environmental-friendliness of the product by confirming the characters and the following marks. Description of TDK environmental icons			product portal		Common Mode Filters / Chokes						Catalog		Common Mode Filters / Chokes Catalog					Status of TDK’s Environmental Responses		Status of TDK’s responses to various environmental standards and measures regarding environment-conscious products		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 19

Can your products be disposed of as normal industrial waste?

Accepted Answer

﻿	Q.Can your products be disposed of as normal industrial waste?EMC Components > EMC Components > Common Mode Filters / ChokesA.Our products can be disposed of as industrial waste.			product portal		Common Mode Filters / Chokes						Status of TDK’s Environmental Responses 		Status of TDK’s responses to various environmental standards and measures regarding environment-conscious products 			Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 20

Please provide the Mean Time Between Failure (MTBF) and Failures in Time (FIT) for common mode filters (common mode chokes).

Accepted Answer

﻿	Q.Please provide the Mean Time Between Failure (MTBF) and Failures in Time (FIT) for common mode filters (common mode chokes).EMC Components > EMC Components > Common Mode Filters / ChokesA.For information on the Mean Time Between Failure (MTBF) and Failures in Time (FIT) for common mode filters (common mode chokes)&#44 please prepare the following four items&#44 and send inquiries to your nearby sales office or distributor&#44 or send inquiries from this website.(1) Product number (2) Usage (CAN communication&#44 etc.) (3) Hours of operation per day(4) Operating environment temperature			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 21

What are the main failure modes of common mode filters / chokes?

Accepted Answer

﻿	Q.What are the main failure modes of common mode filters / chokes?EMC Components > EMC Components > Common Mode Filters / ChokesA.They include open-circuits (disconnection) and short-circuits which are representative of common mode filters (common mode chokes)&#44 as well as the inability to perform normal noise removal due to impedance or to inductance changes caused by core peeling or large chipping.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 22

Can common mode filters / chokes be washed?

Accepted Answer

﻿	Q.Can common mode filters / chokes be washed?EMC Components > EMC Components > Common Mode Filters / ChokesA.The MPZ series and the HF series products require ultrasonic cleaning  [20W/l or less&#44 28kHz to 40kHz&#44 5 minutes or less at a room temperature] The ACM series products can be washed by ultrasonic cleaning using isopropyl alcohol (IPA) or pure water for several tens of seconds. Please be reminded that&#44 since the ACM series products have exposed wires&#44 applying a strong ultrasonic wave or cleaning for a long period of time may cause wire breakage.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 23

Are there any restrictions for wire wound type common mode filters / chokes when a gold foil pattern is used on the circuit board to which they are mounted?

Accepted Answer

﻿	Q.Are there any restrictions for wire wound type common mode filters / chokes when a gold foil pattern is used on the circuit board to which they are mounted?EMC Components > EMC Components > Common Mode Filters / ChokesA.If the connection part of the wire is on the side of the circuit board&#44 disconnection due to "solder erosion" may occur.If the connection part is on the opposite side of the circuit board&#44 there is likely almost no risk caused by "solder erosion."Our product lineup includes products that have a connection part on the opposite side of the circuit board.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 24

Can I apply coating for moisture prevention on common mode filters / chokes?

Accepted Answer

﻿	Q.Can I apply coating for moisture prevention on common mode filters / chokes?EMC Components > EMC Components > Common Mode Filters / ChokesA.The impact of a moisture proof material on the products depends on the type&#44 application method&#44 application amount&#44 or application location of the material; therefore&#44 we cannot guarantee the performance of our products. Please test moisture proof agents on the actual products and independently manage them.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 25

How can I know the composition of the electrodes or terminals?

Accepted Answer

﻿	Q.How can I know the composition of the electrodes or terminals?EMC Components > EMC Components > Common Mode Filters / ChokesA.Please specify the relevant product and please contact our sales representative or distributor&#44 or contact us through this web site			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 26

Can I apply resin on common mode filters / chokes?

Accepted Answer

﻿	Q.Can I apply resin on common mode filters / chokes?EMC Components > EMC Components > Common Mode Filters / ChokesA.In general&#44 they do not support resin application. However&#44 since some resins may be supported&#44 please specify the relevant product and please contact our sales representative or distributor&#44 or contact us through this web site.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 27

Provide instructions on how to measure impedance of a common mode filter / choke.

Accepted Answer

﻿	Q.Provide instructions on how to measure impedance of a common mode filter / choke.EMC Components > EMC Components > Common Mode Filters / ChokesA.Common mode /Z/ is measured by connecting the filter/choke coil as in Fig. 1. Differential mode /Z/ is measured by connecting the filter/choke coil as in Fig. 2.  Fig.1.　Common mode /Z/  Fig.2.　Differential mode /Z/			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 28

What kind of failure occurs when an overcurrent flows?

Accepted Answer

﻿	Q.What kind of failure occurs when an overcurrent flows?EMC Components > EMC Components > Common Mode Filters / ChokesA.In the case of multilayer products&#44 the surface temperature increases when an overcurrent flows&#44 which may lead to damage of the terminals or melting of solder.In the case of wire wound products&#44 it is less likely that the lines of the products themselves have an open failure due to a momentary (usec) overcurrent.However&#44 if a current larger than the rated current flows for an extended period of time&#44 an open failure will occur. 			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 29

What are the reliability test items for common mode filters / chokes?

Accepted Answer

﻿	Q.What are the reliability test items for common mode filters / chokes?EMC Components > EMC Components > Common Mode Filters / ChokesA.For information on reliability testing items for common mode filters (common mode chokes)&#44 please specify the product and send inquiries to your nearby sales office or distributor&#44 or send inquiries from this website. 			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

Question 30

How can I obtain the detailed reliability test results?

Accepted Answer

﻿	Q.How can I obtain the detailed reliability test results?EMC Components > EMC Components > Common Mode Filters / ChokesA.For information on reliability testing items for common mode filters (common mode chokes)&#44 please specify the product and send inquiries to your nearby sales office or distributor&#44 or send inquiries from this website.			product portal		Common Mode Filters / Chokes		Contact Information			  Inquiries on products&#44 sales&#44 or technical matters

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