I'm running an ADAU1701 and have found that my MCLK frequency fluctuates.
Specifically, in master mode, the clock doesn't stay at one frequency. This is leading to a noisy I2S output. I've tried outputting a sine wave and the pitch changes, on top of having a high noise floor.
In master mode, I've also tried taking out the oscillator and used a function generator to generate the clock signal. Surprisingly, the result is the same. Scoping the generator output, I get a clean clock signal. But scoping MCLK from the chip, the frequency fluctuates.
Is this a known or common problem?
Thanks for any help or suggestions.