by Spehro Pefhany <speffSNIP@[EMAIL PROTECTED]
>
Jul 3, 2008 at 11:00 AM
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.
Then the flyback current won't exceed half an amp, and you can use a
1A (preferably fast) diode
>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? Or will the body diode of the
>FET I plan on using (On Semiconductor NTJS4405NT1G,
>http://www.onsemi.com/pub_link/Collateral/NTJS4405N-D.PDF
) be enough?
>
>Thanks!
>
>-Michael
The body diode is not in the correct place, so it won't work. You want
to put the diode across the load.
Best regards,
Spehro Pefhany
--
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