At 12:05 PM 10/02/04, you wrote:

>Eisermann, Phil [Ridg/CO] said:
> >         If I ignore the fet resistance and assume a perfect
> > capacitor for worst-case approximation, then I basically
> > have a 14.4V battery charging a 33uF cap through a 3R9
> > resistor. Following the tech note shows an equivalent 50W
> > pulse for 200usec. So where do I go from here? Is that
> > correct, and is that too much for an 0805?
>
>I seem to recall the max current for an 0805 from the last time I
>researched it being 1 amp peak, but certainly it is not as high as the 3.5
>amps you are giving it, although it's for a short time.
>
>Time to stack four 15 ohm resistors?
>
>Bob

I found an app note on how to calc out the current a while back but
it really depended on free air, mounting style, current, pulse duration, time
between the pulse etc. At best I could get away with was about 75% over the
rating on a through hole that was in the air. I'd imagine surface mount would
be much closer to the original rating as it just doesn't have the cooling.

Dave

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu