andy at openmoko.com
Wed Aug 20 11:22:19 CEST 2008
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Somebody in the thread at some point said:
| On 8/20/08, Andy Green <andy at openmoko.com> wrote:
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|> Somebody in the thread at some point said:
|> | On 8/19/08, Joerg Reisenweber <joerg at openmoko.org> wrote:
|> |> This power removal is done by U1705, and it should relyably cut power
|> when we
|> |> disable IO_3V3 what is quite normal for shutoff.
|> |> No special kernel action required.
|> | This is in a lot of cases a faulty assumtion.
|> When IO_3V3 goes down it goes down... the pcf50633 has special
|> arrangement to bring down "off" regulators to 0V.
| ( Hmm, pull down seems to be only on the LDO regulators 4,5 : 0.8R
| all others : 2k
| GSM sits on one of the switchers? )
GSM has direct access to battery for PA, and via a MOSFET switch for GSM
logic. For PMU switcher regulator performance when "off":
''... A pull-down switch on the output of DOWN1 guarantees an output
voltage of 0 V when the regulator is switched off. A pull-down switch
on the output of DOWN2 guarantees an output voltage of 0 V when
both DOWN2 and MEMLDO are switched off. ...''
p56, and about AUTO (IO_3V3):
''... Pull-down switches on the outputs guarantees an output voltage of
0 V when the regulator is switched off. ...''
| That does not make that much of a difference.
| The chip is (partly) supplied via the IO pins when they are at H level.
Yeah but Joerg is telling you that IO_3V3, the "on while anything is on"
IO power for CPU and most everything else is down when the device is in
"off" state, and I am telling you it means it goes quickly to 0V in this
case as quoted above.
So, which pins still have any high level that can feed GSM side through
protection diodes in this situation? CPU doesn't have any rail above 0V...
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