I am working on a product that uses three TAS5706A stereo amps in 2.0 BTL mode. Our REV B PCB performed admirably with my worst Audio Precision torture tests, such as running a sweep at 20W x 2 into 8 ohms from 20 Hz to 20 KHz. However, our REV C PCB for this product (slated for release to production), has introduced a weakness. Above 11 W x 2, the amplifier immediately goes into some kind of shutdown mode at frequencies form 16.5 KHz to 19 KHz. It will do full rated power below 16.5 KHz, or if I turn it on at 20 KHz. Other facts:
(1) Idle PWM remains during shutdown, it is the audio modulation on it that the amp cuts off.
(2) The modulated PWM at full power comes back after about 2 seconds, and then the cycle repeats itself.
(3) This happens right off the bat on a relatively cool TAS5706A when you hit it with the full amplitude I2S signal at a vulnerable frequency. It does not seem to be thermally rated.