On Tue, 15 Nov 2005 08:31:11 -0500, Olin Lathrop wrote:

>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.
>

Thanks, Olin. You're right, I was going by the write-up and neglected
to confirm that value in the specs section. It's clearly listed as 220
nF minimum as parameter D324.


Regards, Bob

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