No battery Vsys issue is USB overcurrent?

Werner Almesberger werner at
Mon Jun 30 16:33:52 CEST 2008

Andy Green wrote:
> Of course 30us ~= 1/32kHz, we're saying it's for "one pcf clock" that
> Vsys is disrupted -- probably highly significant if we can figure out why.

I see the following profile:

Ext. capacitor	First drop	Second drop
none		1.16V in 48us	1.28V in 16us
10uF		1.48V in 105us	0.88V in 13us

Drops are deltas. Total drop is 1st plus 2nd. There's also an internal
10uF capacitor in parallel.

So I don't really see 1/32kHz anywhere in this. The PMU retries at
exactly 10Hz, independent of the capacitor size.

- Werner

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