Suspend Power Cheat

Andy Green andy at
Fri Feb 15 14:00:02 CET 2008

Hash: SHA1

Somebody in the thread at some point said:
> Andy Green wrote:
>> Obviously this can affect WLAN module state which is supplied by IO_3V3,
>> although GSM doesn't seem to use IO_3V3 any may be fine with it.
> Hmm, we have an awful lot of things hanging off IO_3V3. Are you
> sure none of them go crazy when you lower their supply that much ?

I'm not even sure they don't go crazy when given 3.3V :-)

> It would certainly be a very nice saving. But running half the
> board way out of specs sounds quite radical to me.

Actually the list of IO_3V3 customers is knowable:

 - CPU IO voltage (separate from core voltage)

 - CPU RTC rail for some reason

 - CPU ADC rail


 - Audio AMP

 - USB Host pwr control

 - LCM

 - Motion sensor IO (not core)

 - Glamo IO (not core)

 - WLAN module power

Plus various static pullups on Open Drain lines not being used at that time.

Its a continuum -- we can pull it to 3.0V okay because that is inside
+/- 10%.  What happens at 2.7, at 1.8... shouldn't we test it? :-)

- -Andy
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