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Re: FET G-S voltage limits

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Tim Wescott wrote:
> A customer of mine is repurposing a board that I designed for them
> several years ago, and we're running into some interesting issues.
>
> One of the issues is that there's a master turn-on to the power section
> of the board that's operated by pulling the gate of a P-channel FET low.
> I just noticed that the thing is rated for a maximum G-S voltage of 20V
> -- we had been putting 24V on it (oops), and now we're putting about 29V
> on it (bigger oops).
>
> We're now seeing that part get hot at high current draw, but we've
> identified two other possible mechanisms for that happening.  I'm trying
> to sort through the suspects to find a culprit.
>
> How much does the maximum G-S voltage rating on a FET matter?  Could it
> make a FET overheat at high currents, or would it just cause the whole
> thing to pop somehow?
>
> TIA
>
   My guess is that there are micro gate insulation breakdowns - like a 
pinhole; those will never be seen via a nominal leakage test.
   Perhaps ions are injected at those sites, causing localized 
mis-behavior..

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FET G-S voltage limits Tim Wescott <seemywebsite@myfooter.really> - 2017-03-24 16:34 -0500
  Re: FET G-S voltage limits Joerg <news@analogconsultants.com> - 2017-03-24 14:41 -0700
    Re: FET G-S voltage limits Tim Wescott <seemywebsite@myfooter.really> - 2017-03-24 17:02 -0500
      Re: FET G-S voltage limits Joerg <news@analogconsultants.com> - 2017-03-24 15:42 -0700
  Re: FET G-S voltage limits dagmargoodboat@yahoo.com - 2017-03-24 14:42 -0700
  Re: FET G-S voltage limits John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 15:33 -0700
    Re: FET G-S voltage limits Joerg <news@analogconsultants.com> - 2017-03-24 16:08 -0700
      Re: FET G-S voltage limits John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 16:24 -0700
  Re: FET G-S voltage limits "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-25 03:01 -0500
  Re: FET G-S voltage limits Robert Baer <robertbaer@localnet.com> - 2017-03-30 23:37 -0800

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