GSENSOR_3V3 voltage drop

[Christoph Mair]

> [Christoph Mair So  23. August 2009]:
> > > 2009/8/23 Christoph Mair <ml at chonyota.net>:
> > > > The voltage is now between 3.32V and 3.44V which seems to be ok,
> > > 
> > > Nice.
> > > 
> > > > but after
> > > > suspending it still drops to 2.44V Vmax and 1.78V Vmin (when the 
compass 
> > chip
> > > > starts a measurement).
> > > 
> > > Just to make sure I got you right: You enable the "g-sensor" and get 
about 
> > 3.3V,
> > > then you suspend and _while suspended_ you get 2.4V and 1.8V 
respectively?
> > > What happens when you resume? Do you get back 3.3V? If this is the case 
> > > you probably don't set GPD12/13 (CS), GPG7 (CLK), GPG6 (MOSI) to 0 and
> > > GPG5 (MISO) to pulldown during suspend and leak the voltage from the
> > > CPU. Can you pleasemake sure you set those pins during suspend!
> 
> ^^^^!

> As suspected in my other posting, and explained by Sven, the GSENSOR_3V3 
rail 
> may see "phantom"-feeding by the data(MOSI)/clk-lines if those are at 3V3 
> while LDO in PMU is powered down, during suspend. It doesn't matter if you 
> touch those lines, the feeding may take a path thru the gmeters (the clamp 
> diodes there) so you see some voltage of 3V3 - (voltage-drop on diode).
> Please check as suggested by Sven
GPD12/13 (G1_CS and G2_CS) remain high (3V3) after suspend. This probably 
leaks current into G1/2_INT and SPI_MISO1 which are at 2V4.

Christoph