On Thu, 3 Jul 2008 06:57:18 -0700 (PDT), Michael <nleahcim@[EMAIL PROTECTED]
>
wrote:
>Hey there - I'm putting together a board that will have a number of
>FETs switching the low side of some electromagnets. I do not know what
>these electromagnets will be - but I've been told to design to be able
>to switch half an amp across each.
>
>So, though I don't know anything about the electromagnets - I think
>it's pretty safe to say that they'll be at least somewhat inductive.
>So how should I size the flyback diode?
1N4001, or any cheap power diode, unless mag field dropout time has to
be fast.
Or will the body diode of the
>FET I plan on using (On Semiconductor NTJS4405NT1G,
Nope, wrong direction.
Some fets will let you skip the clamp and just absorb the flyback in
avalanche mode; some will die, instantly, first cycle. Lots of
darlingtons are avalanche rated.
John
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