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Old October 20th 06, 11:17 PM posted to rec.radio.amateur.homebrew,sci.electronics.design
Roy Lewallen Roy Lewallen is offline
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First recorded activity by RadioBanter: Jun 2006
Posts: 1,374
Default PSUs: current-limiting and crowbarring - incompatible?

Most supplies I've seen with both crowbar and current limiting use
fold-back current limiting. When the current exceeds the set limit (due
to too heavy a load or to the crowbar firing), the current drops back to
a level considerably lower than the limit current, and one which the
crowbar can tolerate indefinitely.

Roy Lewallen

wrote:
Hi gang,

Is it not feasible to use a crowbar circuit across a PSU's output if
that PSU has a current-limiting feature? I can imagine a situation
arising where an over-voltage causes the crowbar to close, generating a
short-circuit condition which activates the current limiting. The
output will then be stuck at not enough amps to blow the upstream fuse,
but enough current to smoke the crowbar (which is not designed to be
kept conducting for any length of time of course). Is there some way to
have both over-current and over-voltage protection working together in
harmony?
Thanks.
p.