Am Di 1. Juli 2008 schrieb Andy Green: > Somebody in the thread at some point said: > > |> It all comes down to where is all the current going at startup. We'll > |> get unconfused real quick when we work that out. The regulators are > |> current limited during this phase and shouldn't be able to add up to > |> ~10W that is suspected. It seems the culprit is via Vsys path not via > |> battery directly. > | > | The auto_converter powering IO_3V3 is designed to deliver high > current, and in > | step-down mode probably even might draw way more than 2A, to charge C1707 > | (47u) and dunno what else. I wouldn't rely on current-limiter of this > | regulator on startup. > | To test it might be a simple setup to feed some 3V to IO_3V3 from > external > | powersupply, thus precharging all these Cs - dunno if this would terribly > | spoil anything on startup. However the test is so simple it might be > worth > | it. > > Gah I read this as I just finished doing that test on STBY_1V2, 1V8 and > IO_3V3 rails from a second A5 that was powered first -- the first two > make no difference, but we get a good start on the unit under test if I > gave it "3V3 transfusion" from the other A5. So good idea! > > This is clearly a big clue, but our PMU variant says that it current > limits the Auto regulator to 400mA during its startup.
had no look at the particular power-up sequence. So just an idea: precharge via a diode from some low-power lower-voltage more-early-in-sequence regulator? /j
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