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  1. #1
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    EMI/EMC Compliance scheme

    I am developing a system which is powered by 230V/AC. I am using a AC-DC converter (230VAC to 3.3V/2A-max) to power on board components. I have to make this product EMI/EMC compliant as per IEC61000 standard, essentially for surge and EFT. Now I have the following proposal for meeting the compliance

    1. Choose the power supply already compliant for EMI/EMC (https://uk.tdk-lambda.com/KB/ZWS-B-Datasheet.pdf)
    2. In addition to point No 1, add EMI filter and Surge suppressing devices before power supply as a line of defense

    Please confirm if either of the above proposed method is Ok or should I adopt a different strategy?

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  2. #2
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    Re: EMI/EMC Compliance scheme

    sounds like you are on the right path ...



  3. #3
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    Re: EMI/EMC Compliance scheme

    Hi Easy peasy

    Please confirm, which one to choose,Sl.No.1 or Sl.No2 as described in #1?



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    Re: EMI/EMC Compliance scheme

    No. 2 includes No.1 so both is implied in your post.



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    Re: EMI/EMC Compliance scheme

    Hi Easy peasy

    Sl.No2 requires additional investment, whereas Sl. No.1 is bit cheaper. So I am asking whether Sl.No.1 alone would suffice or should I really go for additional investment?



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    Re: EMI/EMC Compliance scheme

    impossible to tell - the golden rule of EMC compliance is: start with everything you can fit ....



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  7. #7
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    Re: EMI/EMC Compliance scheme

    Hi
    Curious, but can EMI filter (as I proposed) withstand surge (2kV level) and EFT burst transients? The data sheet FN2030,https://www.schaffner.com/product-st...heets/fn-2030/ does not detail about this



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    Re: EMI/EMC Compliance scheme

    perhaps you need to read the data sheet more closely - it clearly states 1100VDC P-N for 2 sec, and other ratings for P->E 2000Vac and 2550 VDC ... 2 sec

    these are a bit light compared to a class Y2 cap - but I guess you get what you pay for...



  9. #9
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    Re: EMI/EMC Compliance scheme

    Hi Easy peasy
    Recently my customer told me that even though the power supply claims to be compliant to surge and EFT, still it is mandatory to provide basic protection for the DC line connected to load.

    In that case, I am not sure where to begin, because I do not know what voltage level will be let through by the power supply and what current levels to assume. My load is FPGA and other bunch of ADC/DAC/op-amps etc. How to calculate the impedance of my circuit and estimate the peak current?



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  10. #10
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    Re: EMI/EMC Compliance scheme

    easy - some 5W zeners on the DC lines ...



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    Re: EMI/EMC Compliance scheme

    Hi Easy peasy

    Some calculation tips would be helpful to choose the right TVS.



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    Re: EMI/EMC Compliance scheme

    reading data sheets and app notes for oneself can be very instructive ...



  13. #13
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    Re: EMI/EMC Compliance scheme

    Looked at references. For protecting 5V DC line, I chose SMAJ6.0A. The clamp voltage suggests 10.5V at Ipp. But max rating for 5V devices are 5.25V. Suggest me the right solution



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    Re: EMI/EMC Compliance scheme

    see post #10



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