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  1. #1
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    TVS Diodes power ratings for IEC 61000-4-5

    Hi,
    I want to put a TVS diode between positive and GND lines (Earth and GND are the same in my board) on my board to pass the surge test (IEC 61000-4-5).
    When you check datasheets of TVS diodes they are mostly mentioned the IEC standards that they support, but my problem is I don't know which package(SMA, SMB, SMC) is suitable for my case.
    If I want to pass the category 4 in surge test which is 4kV Do I need SMC (500W)package ? or SMA package (400W) is enough?
    How can I do the calculation from a TVS diode datasheet to comply with the standard?
    My board is a 48V DC Drive

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  2. #2
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    Re: TVS Diodes power ratings for IEC 61000-4-5

    Hi,

    You may calculate the pulse energy that has to be dissipated by the diode.
    Or you run a simulation doing the math for you.

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  3. #3
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    Re: TVS Diodes power ratings for IEC 61000-4-5

    You should clarify which of the 61000-4-5 test pulses has to be handled by the protection circuit, also what's the intended TVS voltage. TVS ratings are referring to 10/1000 us pulses which have relative low current. Level 4 1.2/50 us test pulse has 2 kA peak current and exceeds the ratings of the mentioned diodes.

    Another point is that sufficient TVS diode rating doesn't guarantee that your circuit survives the TVS clamp voltage.



  4. #4
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    Re: TVS Diodes power ratings for IEC 61000-4-5

    According to my reading of the standard, power lines have to be tested with 1.2/50 µs (8/20 µs short circuit) pulses. You should choose TVS diodes that are specified for 8/20 µs, e.g. Littelfuse LTKAK3 series.



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