Author Topic: EMI Filter in Isolated DC Converter  (Read 743 times)

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Offline Nikos A.Topic starter

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EMI Filter in Isolated DC Converter
« on: June 26, 2019, 01:06:20 pm »
Hi everyone,

I was looking a suggested EMI filter network and I am wondering if the capacitor C4 "breaks" the isolation between the input and output ground

Furthermore, what is the purpose of these high voltage (3kV)  MLCC capacitors C2,C3,C4?




 

Offline madires

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Re: EMI Filter in Isolated DC Converter
« Reply #1 on: June 26, 2019, 02:06:10 pm »
You have answered the second question already yourself. ;) The caps are meant to suppress EMI. To provide sufficient safety for the isolation between primary and secondary side the caps are high voltage types. Of course they pass AC. This is similar to the EMI suppression cap across the flyback transformer in a mains SMPSU, e.g. a wall wart. In your case of a DC input the filter caps could pass a low current when powering on or off.
 


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