On 10 Feb 2004 at 14:46, Eisermann, Phil [Ridg/CO] wrote:
>         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?

Probably way too much. Philips make some high pulse power rated SMD
resistors, look at MMA0204 (1206) and MMB0207 Professional series
resistors. Chances are you will need to go with something with a larger
footprint than 0805.

As the failure rate you are observing is not completely catastrophic, you
might consider increasing the resistor value and/or stacking two resistors on
top of each other. Test it to destruction to find out the real limits though.
Wear safety gogles, kids don't try this at home, have fun!

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Brent Brown, Electronic Design Solutions
16 English Street, Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile/txt: 025 334 069
eMail:  brent.brown@clear.net.nz

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