Bob Barr wrote:
> According to the datasheet for the USB chips, the capacitor between
> the regulator output and ground should be 200 nF (0.22 uF) +/- 20%.

This is in the writeup in the USB peripheral chapter.  The specification in
the electrical characteristics section contradicts this.  The minimum
capacitance is higher than 220nF-20% but the maximum is left open.  I asked
Microchip for a clarification on this a couple of weeks ago.  The
preliminary answer I heard is that 220nF+20% is not an upper limit as the
writeup implies, and that more than 220nF is in fact a good idea.  Their own
board uses 470nF if I remember correctly.  I asked if 1uF ceramic would be
OK, and so far they've said it probably is, but I haven't gotten a
definative answer yet.


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