dont-smoke.patch / Gold cap possibilities

[Andy Green]

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Somebody in the thread at some point said:
> Am Di  25. März 2008 schrieb Andy Green:
>>> Shouldn't we have a goldcap parallel to (maybe removed) battery, to buffer
>>> spikes?
>> It's quite a little area of physical space, 
> 
> Yep, those aren't THAT small.
> 
>> and I pulled the battery 
>> many times and it never made a crash, the PMU is pretty decent at
>> handling that.
> 
> I thought of spikes above 100mA when booting without bat. And this 

You mean that we boot without battery and then we add a battery?  I
don't quite know the response of the PMU in detail but I do know it
won't crash the CPU.  That has to mean it dynamically manages where it
gets the power from very well, that's why the goldcap is more of a
feature I think.

> strange "killersound" when removing bat while charge (only on GTA01?)
> And of course buffer while battchange.

This has gone away on GTA02, some A5s from the earliest batch have
issues coming up without battery and some (most) don't.  I have one that
can oscillate with a quiet tick until it is given a battery and boots.
But the tick comes from powering the mic up and down repeatedly I think
and it seems to be an individual hardware build issue on that device,
because the other one I have doesn't do it.

>> Whether it makes a "feature" if the phone suspended on battery removal,
>> survived for 20 seconds on the goldcap so you can swap the battery and
>> resume, I dunno. 
> 
> I think it's cool :-)

Yes it does provide a new way for the user, access to internal devices
without reset ... if you are quick :-)

>> Inrush current from the battery would need managing 
>> with a series resistor is all.
> Yep, plus a schottky, for discharge. Maybe, depends on R.

Good point.

> Well we may easily retrofit :-) If we can find a space

If the product definition folk decide they want to pay for it :-)  I
guess this is something for later if they are interested and not GTA02.

- -Andy
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