PCM2912A: Schematics review for implementing USB based audio to Xeon SoC

Hi Nihar,

I have reviewed your schematic and have I don't see any issues. To answer your comments in the pdf:

1) It looks like the LED current on REC and PLAY will be ~4mA if we assume VBUS is as high as 5V, the pins are tested with 8mA so there should be no issue there. However, the LEDs you have chosen look like they are intended to be driven with closer to 20mA of current (this is what the specs are tested at) so you may just want to confirm that 4mA is sufficiently bright for your needs.

2) Electrolytic capacitors are not required, they just tend to be much easier to find at 100uF values but the polymer caps you are using look good as well and should still have a low voltage coefficient, keeping distortion low.

3) The film capacitor on your input looks to be good quality as well. I have used similar capacitors on some of our higher performance EVMs and they have excellent distortion characteristics. 

4) The micbias pin is intended to power the microphone you connect. If you are powering your microphones through some other means on the backplane then you can leave this pin floating. Also note that the PCM2912 is a mono-input, so if you have a left and right channel microphone you will want to sum those signals before inputting to the PCM2912.

5) There is no need to split ground planes for this device so you are fine having one ground. Just make sure you abide by good layout practices and maintain good ground plane connections throughout your board.

Let me know if you have any other questions or concerns!

Best,

Zak