next-generation (now) MPU discussion / Backup battery on PMU only

Andy Green andy at
Fri Apr 25 10:32:49 CEST 2008

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Somebody in the thread at some point said:

|> ''The ONLY scenario we consider is no external power, and battery is
|> removed.  Why do we need MSP430 state to survive it?   I don't think we
|> need this since we only want RTC to stay up and the RTC can be in PMU.''
| Well, this statement isn't true in the way we currently use the PMU.
| If the PMU is in its Standby state, all its regulators are down, thus
| the MPU needs some other power source - be it a direct link to Vsys or
| the backup battery.

But the proposal is that the MPU does not need any power at that time...
we just use the PMU power button if things got so bad we had no external
power or main battery and the PMU RTC is ticking over from backup
battery.  What is the downside if MPU is down during this time?

- -Andy
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