BrokenMoko (burnt)

Mike Montour mail at mmontour.net
Mon Mar 16 00:03:39 CET 2009


Werner Almesberger wrote:

> Another theory is that the bead doesn't like 1 A for extended
> periods of time. But then, if this was a general problem, we'd
> see more units with that issue. As far as I know, yours is the
> only one that did this.
> 
> Yet another theory (by Joerg) is that your power supply has a
> lot of high-frequency ripple and the bead had to work extra-hard
> to get rid of that.

When the original reporter said the phone was plugged in all night - was 
this on the Openmoko wall charger? And what state was the phone in? Was 
it running Linux, suspended, off, etc?

I am just wondering if this could be connected to a u-boot bug that I 
encountered last year (see 
http://lists.openmoko.org/pipermail/openmoko-kernel/2008-August/004706.html). 
With that issue a phone connected to the wall charger would rapidly 
toggle the PMU's current limit between 0 and 1A, resulting in spikes in 
the current drawn from the wall charger.

A similar issue is the "Vsys brownout" on A5 boards with a completely 
dead battery (trac #1712), where the PMU tries to start up but the 
system draws too much current and the PMU shuts off again.




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