Management of Power Management ;)

Svetoslav Trochev sal_electronics at
Thu Aug 20 01:45:59 CEST 2009

Svetoslav Trochev wrote:
>> BTW, for a start you can fix SD power control issues (due to a bad
>> merge the function got fubarred), if you run with SD inserted you'll
>> have extra ~20mA feeding card even in suspend.
> Well I just looked the GTA01 schematics and SD card interface an found
> first design problem. ;) It can only account for ~30uA leaking from the
> IO_3V3 power bus to SD_3V3 power bus through R7501 and R7502 when U7501
> is off. I believe we are missing blocking diode that will prevent
> current to flow between SD and IO power buses. (I don't remember if the
> simple diode can stop 30uA leak. )
> Of course you are talking about ~20mA so I guess the problem is in the
> kernel that keeps the power to the SD card on at all time. Right? (
> Signal /SD_ON coming from pin M14 on S3C2410X ).
Great, I just made my first mistake :) After the printing the schematics
on bigger sheet of paper I see that there is no connection between R7502
and R7501 because we have two different signals: /SD_ON and /SD_CD. So
the right signal that powers on/off the card is /SD_ON connected to pin
F4 on SoC.

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