Basic ADC for Audio

[cordobes]

Yesterday I was looking for an ADC converter. Why is it SO hard to find an IC with a minimum of 16 ENOB and 48 [kHz], and that doesn't have a thousand pins. Why isn't there something with INL, INR, SYSCLK, WORDCLK, DATAOUT, V+, AGND, DGND. I feel like I'm missing something, or I'm looking wrong. Does anyone know of an integrated with these characteristics? Any help is welcome.

[ElectricDruid]

Cirrus used to have a load of good audio parts.

https://www.cirrus.com/products/audio/

These days, a lot of the time people want a codec (ADC *and* DAC) so you might do better looking for those. I doubt you'll find anything with only the eight pins you mention, but not everything has to be a 100-pin package. There's some SOIC-24s on their list of ADCs, for example. That's pretty reasonable. There's TSSOP-10s too, which is very close to your eight pins, but I know which I'd rather solder!

https://www.cirrus.com/products/audio/#psearch_T300

HTH

[niektb]

Have you seen the PCM1801?
https://www.ti.com/product/PCM1801
It does list as 16-bit so that probably means the ENOB is a few bits shy of 16 bit but other than that I think it ticks most of your boxes 

[PRR]

That's not "looking for an ADC converter", that has to be an AUDIO converter. No other ADC has quite those specs; and on this forum I assume you are doing audio. Cirrus and TI dominate the market.

> INL, INR,

Analog inputs are almost always differential, + and - pins, because you won't get your THD and S/N goals with shared commons. https://www.cirrus.com/products/cs5361/

The pin-count usually includes reference filtering, redundant commons, overflow monitoring, and other BS. The CS5361 shows 24 pins.

[cordobes]

Cirrus used to have a load of good audio parts.
HTH

Thanks Tom. By the way, many of your ideas on your page were always very helpful to me.

That's not "looking for an ADC converter"

Thanks. Don't get me wrong, posting in a DSP thread, in a DIY pedal forum means we are all on the same page: audio spectrum. However that doesn't mean we have to look for integrateds from companies that manufacture specifically for audio.
Microchip, for example, offers the MCP33131, 14 ENOB @ 1Msps.
I know it's single ended, but for 5 bucks, it's worth a try @ 44.1 ksps.
My post refers to the fact that I couldn't find another IC that doesn't have, as you said, as many BS pins, and with minimum specs as to sample at 16b, 44.1ksps.
Obviously using a codec is the way to go, but it struck me that there is no ADC or uC that incorporates something like that, and can be used for minimum quality audio.
Generating a DAC with multiple PWM is trivial, especially with FPGA.

[ElectricDruid]

Obviously using a codec is the way to go,

Yes.

but it struck me that there is no ADC or uC that incorporates something like that, and can be used for minimum quality audio.

Well, there's my ol'favourite the dsPIC 33FJ128GP802. That has multiple 12-bit ADC channels and a stereo 16-bit DAC on the chip. The ADC isn't bad, and the DMA is really handy, but the DAC only has 14-bits of accuracy and is noisy (hardly surprising on the same silicon as a uP). It's somewhat better than "minimum quality audio", but it's not hi-fi.

[Ice-9]

For a decent audio codec you might want to check out the CS4220 although it is no longer manufactured it is available as the same IC form Coolaudio as the V4220. It is a nice codec and will be one of my upcoming forum projects soon. The codec is wel worth looking at in my opinion.

[tommy.genes]

Simple (?) questions: if your codec has differential inputs and/or outputs, how do you interface that to 1/4" guitar jacks? Do you just connect one of them to the tip and ground to the sleeve?

Also, do you have to bias the inputs around the center voltage (V/2, typically 4.5 V in a 9 V pedal) like you do with, say, a single-rail opamp?

I'm thinking of building an I2S-based audio interface for a Raspberry Pi, so I've been looking at codecs lately. It seems like a lot of the parts referenced in many DIY projects are being discontinued, though.

Daisy Seed was using the WM8371 but that was discontinued. Now they are using PCM3060, which looks to have single-ended inputs but differential outputs.

-- T. G. --

[niektb]

Simple (?) questions: if your codec has differential inputs and/or outputs, how do you interface that to 1/4" guitar jacks? Do you just connect one of them to the tip and ground to the sleeve?

Also, do you have to bias the inputs around the center voltage (V/2, typically 4.5 V in a 9 V pedal) like you do with, say, a single-rail opamp?

I'm thinking of building an I2S-based audio interface for a Raspberry Pi, so I've been looking at codecs lately. It seems like a lot of the parts referenced in many DIY projects are being discontinued, though.

Daisy Seed was using the WM8371 but that was discontinued. Now they are using PCM3060, which looks to have single-ended inputs but differential outputs.

-- T. G. --

Yes you can route the negative input to ground. What you could do is a dedicated ground trace from the jack to the ADC and route it as a diff pair (and the ground connection would be made at the jack side) to improve noise performance.

Typically the ADCs take care of their own biasing so all you need to do is insert an AC-coupling cap

[amapst]

There is no such thing as "looking for an ADC converter"; instead, a AUDIO converter is required. No other ADC has specifications quite like that, and based on this thread, I guess you work in audio. The market is dominated by Cirrus and TI.