[gta02-core] More audio considerations

[Rask Ingemann Lambertsen]

On Fri, Oct 09, 2009 at 12:03:07PM -0300, Werner Almesberger wrote:
> From discussion with Joerg on IRC:
> 
> - HP/SPKRVDD are fed by AVCC_CODEC, which is fed by CODEC_3V3, which is
>   fed by LDO2. LDO2 has a maximum current of 50 mA. Joerg says we need
>   at least ~150 mA.
> 
>   So that's a big problem. Thanks for catching it !

   Definitely.

>   GTA02 supplies the audio amp directly from VB, but since HP/SPKRVDD
>   are limited to 3.6 V, we can't use VB (or VSYS) directly.

s/GTA02/GTA01/

> Oh, and did anyone notice that the audio amplifier is not powered in
> GTA02 if running from USB with the battery removed ?

   My GTA02 hasn't noticed yet, no.

   (For a moment I thought you were right, until I noticed that the speaker
was about half a metre away from the rest of my partially disassembled Neo,
thereby providing a plausible (and correct) explanation for the missing
audio output.  :-)

> Opinions ?

   I'd say reassign the PMU LDOs. I can't imagine that their overcurrent
protection won't be sufficient to prevent damage.

-- 
Rask Ingemann Lambertsen
Danish law requires addresses in e-mail to be logged and stored for a year