Post Go back to editing

ADAU1361 differential amplifier not working, no internal bias on input pins - damaged part, or just misconfigured?

I'm bringing up a new design that utilizes an ADAU1361, and I've run into a bit of a snag that I'm hoping is just due to a misconfiguration of the device, but which I fear is actually evidence that the device itself is damaged (with everything being out of stock at all the reputable suppliers, one has to get parts from where one can find them...).

The datasheet for the ADAU1361 notes that all of the input pins are internally biased at AVDD/2, which in my case is 1.65V. On my board, I'm expecting a pseudo-differential input signal on only the left differential input, and thus have my signal on LINN and LINP is tied to CM. I'm not using the right input, so I've tied both RINN and RINP to CM as well. The input signal is connected via a 10uF capacitor, as shown in the datasheet.

The ADAU1361 is connected to an ADAU1452 DSP, which is configured to just pass the input signal straight to the output for testing.

When I probe LINN with no signal being supplied, I expect to see it sitting at 1.65V, but instead it reads at 0V. No matter how I try configuring the left record input in Sigma Studio, I can't seem to get anything to come through the differential input. However, If I take my input signal and jumper it over to the LAUX pin, and route LAUX through to the ADC, the audio comes through as expected, goes through the DSP, and finally is output by the ADAU1361.

Is the differential input on this codec fried? I do have a few more ADAU1361s I could try swapping out, but I wanted to make sure that I wasn't just missing something in the configuration that would cause this behavior. Given that the datasheet states that the input pins should all have a AVDD/2 bias, and I'm not seeing that on the LINN pin, I am thinking that the part is just defective and I should try swapping it out for a new one. If need be, I could also try cutting the trace connecting CM to RINN and using the right channel as my input, but if the left differential input is fried I'm not too confident the right differential input is going to be any better!

Any suggestions for things I could try before I just swap the codec for another from the batch I've got?