Re: Power On Self Test

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.arch.embedded
Subject	Re: Power On Self Test
Date	2020-10-03 18:22 +0200
Organization	A noiseless patient Spider
Message-ID	<rla8gm$trf$1@dont-email.me> (permalink)
References	(8 earlier) <rkhnr4$idr$1@dont-email.me> <rkhut9$vh4$1@dont-email.me> <rki1l6$hr1$1@dont-email.me> <rki9bm$75r$1@dont-email.me> <947ec9a8-1f61-45b9-a742-1fd6d9b6c2d4o@googlegroups.com>

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On 03/10/2020 02:29, Dave Nadler wrote:
> On Thursday, September 24, 2020 at 10:10:05 AM UTC-4, Don Y wrote:
>> Failures rarely occur when the device IS off. But, the act of
>> removing power to a device is just as hazardous as APPLYING power.
> 
> Absolutely!
> My two favorites, sadly seen multiple times in shipping systems where
> I was asked to find out what happened, both involving capacitors:
> 
> 1) Large cap added to uC ADC to 'smooth things out'.
> Guess where that stored energy goes when power is removed?
> 
> 2) Large cap after secondary linear regulator.
> Guess where that stored energy goes when power is removed?
> 

I like to put a diode from each low-voltage power lines to the next
higher voltage line.  That way you get simple and clean power-off
sequencing automatically.  (Yes, that's a little bit of a simplification
- if you've got boost regulators, standby power lines, etc., then it
gets more complicated.)

Thread

Power On Self Test pozz <pozzugno@gmail.com> - 2020-09-23 12:13 +0200
  Re: Power On Self Test Don Y <blockedofcourse@foo.invalid> - 2020-09-23 03:57 -0700
    Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-09-23 14:13 +0200
      Re: Power On Self Test Richard Damon <Richard@Damon-Family.org> - 2020-09-23 08:51 -0400
        Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-09-23 16:03 +0200
          Re: Power On Self Test Don Y <blockedofcourse@foo.invalid> - 2020-09-23 09:36 -0700
            Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-09-23 21:02 +0200
              Re: Power On Self Test Don Y <blockedofcourse@foo.invalid> - 2020-09-23 12:32 -0700
                Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-09-24 11:10 +0200
                Re: Power On Self Test Don Y <blockedofcourse@foo.invalid> - 2020-09-24 04:11 -0700
                Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-09-24 13:58 +0200
                Re: Power On Self Test Don Y <blockedofcourse@foo.invalid> - 2020-09-24 07:09 -0700
                Re: Power On Self Test Dave Nadler <drn@nadler.com> - 2020-10-02 17:29 -0700
                Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-10-03 18:22 +0200
                Re: Power On Self Test Dave Nadler <drn@nadler.com> - 2020-10-03 09:27 -0700
                Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-10-04 12:48 +0200
                Re: Power On Self Test Don Y <blockedofcourse@foo.invalid> - 2020-10-03 12:08 -0700
              Re: Power On Self Test Paul Rubin <no.email@nospam.invalid> - 2020-09-23 13:05 -0700
                Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-09-24 11:15 +0200
          Re: Power On Self Test Richard Damon <Richard@Damon-Family.org> - 2020-09-23 21:55 -0400
            Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-09-24 11:26 +0200
              Re: Power On Self Test Richard Damon <Richard@Damon-Family.org> - 2020-09-24 09:01 -0400
                Re: Power On Self Test David Brown <david.brown@hesbynett.no> - 2020-09-24 16:21 +0200
  Re: Power On Self Test Mike Perkins <spam@spam.com> - 2020-09-23 23:13 +0100
    Re: Power On Self Test pozz <pozzugno@gmail.com> - 2020-09-24 09:18 +0200
      Re: Power On Self Test Mike Perkins <spam@spam.com> - 2020-09-30 15:14 +0100

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