Questions tagged [common-mode-choke]

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EMI Filter design capacitors problem

I'm trying to design an EMI filter for a 3-phase induction motor driver. I've looked at some example filter designs but in one of them I couldn't understand the capacitors and resistors what they are ...
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47 views

Common Mode Choke question

I have one question which I encountered during usage of common mode choke. Question : "If a common mode choke is used on the main power / ground input, ensure that no I/O circuits effectively bypass ...
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113 views

How to design a CMC (Common Mode Choke) footprint to allow no-pop solution

How would you design in CMC's with a 0504 (1210 metric) 4-lead package to allow for a no populate (do not pop, DNP,DNI) solution? I am thinking 0402 0ohm (zero ohm) resistor but cannot picture the ...
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24 views

Where does the (even-mode) interference come from?

I have a question regarding the differential connection of a surface acoustic wave (SAW) delay line element. When I connect the filter asymmetrically, i.e. at each port one half of the interdigital ...
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41 views

Low-Speed CANbus Common-Mode Choke Insertion Loss

I'm designing a low-speed CAN transceiver breakout-board (schematic below) and I'm trying to select the proper choke to use to reduce common-mode noise. I've found a few common-mode chokes meant ...
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3answers
132 views

What is a power factor correction choke (PFC choke) and how does it work?

They Exist This Link at Newark displays "Power Factor Correction Chokes", which I did not know existed. I have a linear motor which I suspect really needs power factor correction. Please tell me ...
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1answer
123 views

PCB Layout - Common Mode Choke

Why it is recommended to not to add copper planes and to avoid routing of signals under the common mode chokes?
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47 views

Common Mode Noise on Differential Lines Driven Against Chassis GND

How is common mode noise filtered on differential lines that have a noise source that is driving them relative to chassis GND? I drew a picture of what I am imagining below. Imagine a PCB with ...
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77 views

Common Mode Chokes

Consider the following : If we need to figure out the input impedance seen by the source, it will be equal to --> Zin = jw(30u) -jw(27u)+1k+jw(30u)-jw(27u). The first two terms are due to the drops ...
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1answer
58 views

Common mode filters effectiveness

As we know, there are many types of common mode filters that can be implemented. One of this type is a single element topology where this element can be a series impedance element (usually R or L or ...
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147 views

Common mode choke selection for 5V 1A smps power supply

I am designing a flyback smps power supply circuit and having trouble deciding the exact common mode choke that I should use. My power supply specs are as follows: Input - 80-270 VAC 50/60 Hz Output -...
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35 views

dual rail DC/DC convertor and CMC

I have a DC/DC convertor that tales 5V and makes + 15V and -15V rails My question is how to place common mode chokes to reduce common mode noise. Should I place 3 of them (1 on the negative to Gnd , ...
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1answer
238 views

Common mode choke parameters CAN circuitry - split termination concept

I am trying to the understand the important parameters of a common mode choke that will be placed at the CANL and CANH lines of a transceiver. First parameter: Impedance as function of frequency - I'...
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1answer
128 views

Using CM Y capacitors after CM chokes

Below shows the effect of a CM choke on the CM interference: And below is a CM choke with ferrite ring for a USB cable(there is no capacitor installed): In above examples there are no Y caps to ...
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1answer
171 views

Can a common mode choke be used at the output of an SMPS?

If there is CM EMI on DC power supply lines, can a CM choke be used at the output of SMPS supply? Im asking because all CM examples I saw are for AC power lines.
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170 views

Why are there different ways of winding a common mode choke?

Below shows two types of CM choke winding: Is there a difference betwween two in applications? They are both used in literature, yet I havent seen a single sentence abou the digg
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48 views

Is this setup proper to observe the attenuation effect of a common mode choke?

I'm trying to prepare a setup to see the effect of this torodial ferrite ring.. Even though I still didn't understand what way to wind wires to obtain a common mode choke(I saw differnt ways of ...
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388 views

common mode choke - symbol and orientation

I was wondering why there are different symbols for common mode chokes and if/how they affect the way I have to connect them. (upper image incorrect but left for understanding the comment from @...
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1answer
120 views

Common mode chokes in series

I am designing an ultralow noise audio board. On the first PSU PCB (just talking after bridge) I have a CMC to remove switching noise on diodes to undetectable levels (with plenty of capacitance for ...
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158 views

common mode choke and derating vs current

I have a CMC that has is rated at about 1kR at 100Mhz at 3A However my circuit uses only 1A. Do I need to derate my inductance since there is less current flowing through it ?
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1answer
70 views

x2y caps and common mode chokes (using both)

I am designing a ultralow noise PCB board. Common mode noise has to be minimized, so I have a question I am planning to use a CMC on power input and to further decrease the common mode noise I also ...
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1answer
126 views

Choosing toroid for FM dipole choke

After several failed attempts to buy simple rabbit ears for FM tuner I decided to make my own. Now, I have zero knowledge in RF circuits. While finding the formulas for pole length wasn't hard, I ...
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409 views

USB chokes for USB power

We are designing a ultra low noise USB 2.0 hub. I am thinking to add a common mode choke to + and - of the USB connector, in addition to the D+ and D- choke to remove the common mode noise. I am ...
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2answers
252 views

Does a 3-winding common mode choke work on PE wire

Update It was pointed out the PE wire has to carry large current in fault condition so using a 3-phase CMC is problematic. In IEC62368-1 (2nd edition) chapters 5.6.3 and 5.6.4 it is implied that the ...
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2answers
252 views

Why is common-mode noise on a power line bad?

I've always been intrigued by common-mode noise, as it seems to be such a pertinent issue when it comes to op-amps, chokes, etc. used as solutions to remove it. I understand from a digital signal ...
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287 views

know the parameter of common mode choke for power adapter [closed]

How to choose right common mode choke in my power supply design? What are the parameters we have to consider during selection? Thanks Deep
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304 views

does the orientation of a choke in an LVDS application matter?

I found the diagram below online while looking for information on the orientation of a choke I intend to use in an LVDS application. Does the orientation of the choke matter? The part I intend to use ...
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1answer
548 views

common mode choke placement in smps

I am designing a hi end SMPS and I have 1 CMC on the input (ac line) and a second on the DC output. My question is where to place this second CMC. Usually its best to place filters right at the ...
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432 views

common mode choke on DC line

usually common mode chokes are used on AC lines to take care of common mode noise. If I am using a CMC on a DC line ..would the inductance degrade ?
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505 views

Are common and differential mode chokes interchangeable?

Is it possible to use a common mode choke as a differential mode by switching around one pair of wires and v.v. as shown on the drawing? Intuitively it seems that this should work. I need a power ...
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2answers
217 views

Failure of Bourns Common Mode Chokes, Series SRF2012

I work for a company that designs and manufactures electromagnetic flow meters. One component, a Bourns common mode choke, PN SRF2012-361YA, seems to have a failure rate in the field of approximately ...
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1answer
315 views

Common-mode chokes in series

Is it common practice to combine common mode chokes back-to-back in series to eliminate/reduce RF interference in different frequency bands? As a random example, placing this in series with this in ...
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1answer
142 views

HV Pulse Blocking with Common Mode Choke

I need to apply a reset current to a magnetic core on the same circuit as a ~25kV 30ns long pulse. I know there are a number of ways to do this, but for simplicity sake I would like to protect my ...
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1answer
952 views

Common mode choke in circuit with multiple ground connections

I'm designing an automotive circuit where I'm using a reference power design from TI. Together with protection circuitry, this design includes a common mode choke. The same circuit has an antenna ...
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2answers
975 views

Why are the transformer windings in series with line and load in this circuit?

I came across this switching power supply circuit and I noticed the transformer is connected in a way I had never seen before. What is the benefit of connecting it like that? And why does the circuit ...
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1answer
6k views

How can I model this common mode choke in circuit in LTspice?

How can the common mode choke in below diagram used in LTspice? By an inductor or transformer? How should be the circuit drawn in LTspice? I want to use this to filter out CM noises for single ended ...
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2answers
374 views

How does a CM choke reject common-mode noise while allowing the signal of interest? [duplicate]

As far as I know a CM choke is nothing but a transformer(?). How does it block common-mode noise and pass the signal of interest? Should we think of it as an LR filter? And how to size it if we know ...
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538 views

Is this a suitable common mode choke?

I've got a system here where I get 12V DC from a laptop charger which is connected to the wall. That 12V gets stepped down to 5V using the TPS56221 buck converter (running this at 500 kHz, with an ...
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3answers
7k views

What exactly happens to the signals hitting a common mode choke?

I'm trying to better understand the principles behind the common mode choke. I made a few drawings to clarify.   Differential Mode Signals Differential currents (driven by differential voltages)...
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4answers
96 views

What kind of filter is this?

This is very similar to how common mode chokes work but can we implement this by using transistors? Lets assume we have a signal 's' we are trying to amplify.We feed this signal into some linear ...
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2answers
2k views

Why does this isolation transformer have another transformer in it?

The isolation transformer I'm looking at: http://www.mouser.com/ds/2/336/HX1188NL-515471.pdf My question is why is it there? Is it not enough to have just the transformer on the left?
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2answers
8k views

How to eliminate noise from switched power supply

I have an isolated switching power supply (120v in, 12v out) that gives an output shown in Figure 1 when referenced to the output ground (I'm not TOO worried about that noise). The bigger issue I have ...
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1k views

Can I use a common mode choke as a coupled inductor in a SEPIC converter

I do not really understand the difference between common mode chokes and coupled inductors. They are both 2 coils wrap around the same core but I know they have different purposes. I want to design a ...
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1answer
1k views

Common mode choke vs individual inductors for offline flyback smps

I am working on Viper22a based offline switcher and I was going through similar app notes by ON semi and ST. I found two different implementations of noise filtering on incoming mains. This one uses ...
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2answers
752 views

What is the difference between the rated and withstand Voltage?

In case of a common mode choke, I have seen in two different component manufacturers these two terms: rated voltage withstand voltage Are they the same? How are they related?
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1answer
269 views

Selection of filters (common mode and differential mode)

I am designing a flyback converter that works at an operational frequency of 100kHz. Now, I need 2 levels of filtering at the input phase viz - common mode filter and differential mode filter. The ...
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1answer
206 views

Using a COTS common mode choke on DC

Are commercially available common-mode chokes, such as one you'd pull out of a dead switching supply, suitable for DC service up to their rated current, or will they saturate/do other baleful things ...
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2answers
1k views

selection of common mode choke

I want to select a common mode choke. This will be placed at the input of a buck regulator. Now, assuming conducted noise or common mode noise, will be at a certain frequency and I will need common ...
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5answers
13k views

Ferrite bead vs common mode choke

simulate this circuit – Schematic created using CircuitLab I inherited the top circuit from a previous designer on my robotics team. The circuit uses two ferrite beads, a zener, a TVS and a ...
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1answer
8k views

How to use common mode choke inductors? (differential vs common mode)

I have yet to undestrand exactly how to use common mode chokes inductors, according to the datasheet they have 2 operation modes like in the picture common mode and differential mode, however im ...