Vsys oscillation vs 3.3V rail

Andy Green andy at openmoko.com
Tue Jul 1 16:14:33 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| Am Di  1. Juli 2008 schrieb Andy Green:

I mentioned before once the backup battery was happy I started seeing
multiple goes quickly on Vsys, I noticed that when it does this, the
effect on 3.3V rail is cumulative.  (See the attached pic).

The number of goes it has before stopping and waiting for 30ms for the
next batch is highly erratic and variable and it seems that is also a clue.

Again I tested bringing external 3V3 to IO_3V3 and it causes the device
to start OK without battery.  I tried it via 150R and it worked
sometimes, but after that it needed shorting again to make it work, not
sure what changed.  It lifted the starting level of the 3V3 rail
depending on the series resistor, so maybe the variability is down to
the same thing that decides the number of tries on Vsys in quick succession.

| Yeah, just heating my iron to do the same on mic (noise) side to proof
some of
| the alternative reworks I suggested.
| So at the end of the day we will need a good beer both of us ;-)

Sadly not a booze day here but have one for me.

- -Andy
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