Am 12.03.2014 um 16:09 schrieb Michael Mrozek:
Am Wed, 12 Mar 2014 14:29:16 +0100 hat "Dr. H. Nikolaus Schaller" hns@goldelico.com geschrieben:
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)
Those are for charging, right? Are there any differences in terms of handling?
No, fuel gauge.
Well, the BQ27200 is smaller.
The OpenPandora uses the BQ27500.
- find a 600mW replacement for the TPA6110A2 audio amplifier (we have
600mW speakers with 1000mW peak)
The old Pandora one had...?
TPA6110A2 according to the BOM list I have.
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...
There is a reason for it. Using Pandoras headphones port, you can connect most passive speakers and they are loud enough. With 3DS, PSP, etc., you need another amplifier or active speakers.
Or did the Pandora have less than 1W?
Well, the TPA6110A2 is specified for 150 mW @ 16 Ohm which may be the main reason why internal / external speakers are so weak.
On the GTA04 we use the TWL4030/TPS65950 Class-D amplifiers for the speaker(s) and the additional headphone output and have very good sound.
That is what makes me ask in which direction we need improvements.
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?
Since Michael just joined the mailing list and is pretty good with audio, maybe he can help us out here.
Yes, I would appreciate that and is the reason why I brought up this question on this list.
The most important thing is that there's nearly no noise or static, neither when connecting headphones or a speaker.
That can be achieved by almost any circuit - if designed carefully. The main problem are capacitors that are not/still charged and make a "plop". This usually needs an anti-plop-FET.
Audio conversion should be pretty good as well. I think the Pandora uses a 24bit DAC, which is what we should also use (at least).
Well, it is difficult to hear 24 bit for the average user but it is good for marketing :)
Michael should know more about that as well, and remember what characteristics a good DAC needs to have :)
My main concern is: * small * cheap * low number of passive components (i.e. integrated amplifier) * multiple outputs * flexible * not too highly integrated package (no BGA) * standard interface (PCM + I2C)
BR, Nikolaus