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From: "Ken Taylor"
Subject: Re: A protection problem
Date: Wed, 8 Jan 2003 11:23:53 +1300
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"Frank Bemelman" wrote in message
> "Ken Smith" schreef in bericht
> > I'm currently working on a voltage regulator with a major protection
> > problem. The specs are:
> > (1)
> > Input voltage 23 to 28V. This is easy enough.
> > (2)
> > Output voltage DAC controled 0 to 25V (doesn't need to boost make 25V
> > input is too low). This isn't too hard.
> > (3)
> > Output current limited at 100mA. This isn't too hard.
> > (4)
> > Some moron may hook a (+) or (-) 600V supply to the output. This 600V
> > supply can supply a zillion amps so MOVs aren't the answer. PTC devices
> > don't seem to be able to handle this case either.
> > I'm tinkering with various active circuits but they all seem to end up
> > with quite a few parts in them. Does anyone have an idea?
> Since fuses are out of the question, it would have to something with
> a relay that disconnect the 0-25 supply from its output terminals.
> IOW, a circuit that uses a OVP, measures the current through the
> OVP, triggers a flipflop and energizes the relay. The flipflop
> can only be reset by removing the input power 23-28V.
> Frank Bemelman
> (remove 'x' & .invalid when sending email)
This is where I was headed - it seems like the way to go.
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