Suspended mode

Andy Green andy at
Wed Feb 13 08:51:36 CET 2008

Hash: SHA1

Somebody in the thread at some point said:
> Hi Andy:
>> I will remove it to test the 2V on GSM VBAT.
>> Well it won't be a big difference but it shouldn't make it any worse :-)
> I remove R1519 and I set the modem UART (TX,RX,CTS,RTS) to input. 
> The VBAT doesn't have any voltage. 
> Therefore, pull high resistor (R1519) is the source voltage of GSM modem.


> Today, I will found what device consume the 5mA current what device with 3.7V.
> For now, suspend mode, we will turn off GSM, BT, WLAN, and AGPS. 

That will be really extra mega interesting!

I took a look at the PMU datasheet yesterday and it was saying ~50uA in
suspend for itself IIRC.  I wasn't certain that the 250uA (not 220, my
error) figure for selfrefresh is all we could expect for the CPU SDRAM.
    Well we have to have PMU and SDRAM powered, really we didn't need
much else in a really minimal suspend.

Things like WLAN we have to rely on their powerdown, I don't know the
figure for them.  But it seemed that if we were Gods and we did every
little thing right (with GSM and everything OFF), we could imagine to
maybe see Vb suspend current ~1.0mA say?  It suggests there are some
things to find still.

- -Andy
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