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
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?
- find a 600mW replacement for the TPA6110A2 audio amplifier (we have
600mW speakers with 1000mW peak)
The old Pandora one had...?
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?
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.
The most important thing is that there's nearly no noise or static, neither when connecting headphones or a speaker.
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).
Michael should know more about that as well, and remember what characteristics a good DAC needs to have :)
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
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
Hi Michael,
Am 15.03.2014 um 21:00 schrieb Michael Weston:
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.
Well, if we think about using a different chip I still have to choose between: * BQ27421 - http://www.edn-europe.com/en/ti-increases-accuracy-for-li-ion-battery-fuel-g... * BQ27621 - http://www.ti.com/lit/ug/sluuap5/sluuap5.pdf
The main difference is that the BQ27421 has a built-in shunt resistor which means all energy is flowing *through* the chip. If we assume 2A@4.2V this is quite a lot for the small BGA balls... So I fear some voltage drop by the copper wires connecting the BGA.
On the other hand I am not sure how well the BQ27621 really is because it works even without any shunt...
- 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.
Well, like the TWL4030 original design... In the GTA04 we use the TPS65950 and it works really well.
But that is what ED likes: that the speakers are simply fed through the headset jack so that he can connect external power speakers. And that the (analog) potentiometer is controlling both.
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.
Yes, it is an unfortunate 0.4mm BGA. The good side would be that we have software for the OMAP5 ABE (an indepedently powered audio processor on the SoC).
There is also the TWL6041 in a different package. Have to check if that is easier. Anyways they have too much drive power (1.5W) so that we can burn the speakers.
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.
I think they have many different variants.
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.
Ok, I see.
So I will take some minutes to browse through the TVL320AIC options.
BTW: the N900/Neo900 is planned to use the tvl320aic34 (because they have some software and kernel drivers). Maybe this is already a good choice.
But it may not be compatible with using an analog potentiometer.
If we want to use a simple amplifier maybe this is the right one (although design is 10 years old):
http://www.ti.com/lit/ds/symlink/lm4666.pdf
More ideas on this topic are welcome :)
BR, Nikolaus
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
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