Hi Nikolaus (and everyone!),
This looks like a fun project and it saddens me to be almost a bystander this time, but still glad to be included! I am happy to help in any way you would like but I won't be stepping on toes trying to take over anything. I do have some opinions to share about this email.
- should use the BQ27500-V130 or could use the BQ27200 (which appears to need less
external components)
The 27500 is a pretty mature chip now and from what I remember over the years, TI keeps creating new ones that might be better. I didn't like the 27200 back in the day (it's even older IRC) because it had a different way to calculate battery life, I think. I don't think Notaz liked the way the 500 worked and I spent a fair bit of time creating the configuration file for it in order for it to profile the actual Pandora battery.
- find a 600mW replacement for the TPA6110A2 audio amplifier (we have 600mW speakers
with 1000mW peak)
I use an amp that is capable of 1W in the headphone amplifier I built years ago. The problem is that it is a power hog (class-AB) and you'd want a class-D for anything driving those speakers. Some sort of combo amp with a class-AB for headphones and class-D for loudspeakers would be best.
Or should we use a completely different audio codec (like the twl6040?)
I wouldn't recommend that chip if it is going on the main board or you will end up with multi-layer, HDI, and maybe even laser drilling because it was meant to sit next to an OMAP chip that already requires that technology. Wolfson and TI make plenty of chips that will give an amp plus mic driver and I had done some research back in the day when Pandora 2 was still happening.
Or some other TVL320AIC?
That's actually the exact part I was investigating for Pandora 2 years ago. I even bought an evaluation board for it so that I could see how it sounds. I don't have the board in front of me but I'm pretty sure it was a part with mic input, amp out and headphone outputs. The headphone output was nothing like the current Pandora's (power and voltage rail wise) so it was a bit of a trade off. I never did fire it up to hear how it sounded.
Michael
Dr. H. Nikolaus Schaller hns@goldelico.com wrote ..
Hi, I am working on the Version 3 prototype schematics and wonder if we
- should use the BQ27500-V130 or could use the BQ27200 (which appears to need less
external components)
- find a 600mW replacement for the TPA6110A2 audio amplifier (we have 600mW speakers
with 1000mW peak)
BTW: we probably can't simply use the same circuit as for the OpenPandora since driving an external headphone with 1W is a little high... Or should we use a completely different audio codec (like the twl6040?) that has multiple DACs, can driver multiple speakers, headphones and microphones without much external circuitry? The only downside of the twl6040 is that it comes in a BGA package which drives up the number of layers of our main board (because it should NOT go onto the CPU board).
Or some other TVL320AIC?
http://www.ti.com/lsds/ti/audio-ic/audio-codec-product.page#o4=ACTIVE&p1...
Any suggestions? Comments?
BR, Nikolaus