I purchased a pre-made board using the TAS5611 chip with the view to integrate them into a product design, however when I input voltages above 16 (up to 31v), I get a constant high pitched squeal come through the speakers, independent of volume setting. The squeal changes in pitch/frequency with the voltage change, as though I where stepping through a sine wave frequency test tone and it's volume is loud enough that it its physically uncomfortable and cannot be drowned out by the music.
I have tried a transformer based lab supply and a switch mode based lab supply with the same result. My test rig is the same one I used to test various 3116, 3118, 3111, etc boards and changing boards confirms the issue resides with the tas5611 board.
The board uses a pair of OPA 1632 and the additional power for the amp and them I assume comes from an LM2755.
Any suggestions on what might be causing this and things I could try to fix it?
