gEDA-user: bypass caps

Stuart Brorson sdb at cloud9.net
Mon Aug 21 15:26:49 EDT 2006


> Also remember that NASA recommendations tend to be super conservative.

I would normally agree, except that NASA's 60% rating suggests using a
10V cap to hold off 6V, which seems too low to me.  A 2X derating 
would suggest at least 12V to stand off 6V, whereas my 3X derating
guideline says at least 18V rated caps.  I don't know why NASA
suggests only 60% derating.

> Also 
> don't derate *too* much: I've gotten my wrist slapped by a NASA R&QA guy for 
> using 50V ceramic bypasses in 5V circuits.

10X derating is waaaay over the top, don't you think?  But if the caps
come in the same footprint as 15V caps, say, then why not?

Stuart


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