current focus / Removing PMU problem in future

Andy Green andy at openmoko.com
Fri Jul 11 15:25:54 CEST 2008


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Somebody in the thread at some point said:
| Andy Green wrote:
|> VB_SYS failure (something that "sticking a big cap on VB_SYS" does not
|> really do).
|
| Yeah, FETs + MPU beat caps :-) Powering the MPU becomes a bit tricky,
| though, since we can't use the secondary side of the PMU. We could
| use VB_SYS, though.

We would need to hit SHUTDOWN or something within some tens of ms to
stop it trying to power up completely from USB insert, etc if previously
otherwise unpowered since we come up at the same time as the PMU
basically then.  No real problem.  And VB_SYS has the big advantage it
is already "mixed" from the power sources.

| We'll have to give that MPU one more try soonish. Oh, and look what
| I found. I'm sure there's also someone who makes these same kind of
| thing a little cheaper.
|
| http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=WM2072-ND

That's a whole other (zombie) battle :-)

- -Andy
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