I'm designing an audio public address system, where I use TPA3221 for amplifiers. I attached my design below.
At the output of the amplifier (Port OUT1+ / OUT1-), I connect to a matched audio transformer (this model: https://edcorusa.com/products/ea75-75w-bidirectional-audio-distribution-transformer).
Out+ connect to "4 Ohm" terminal, Out- connect to "Common" terminal. But when I power up the PCB with 24V supply, PVDD pin get smoke and burn out very quickly. (at that moment, the secondary side of the transformer is
left open). I tried with another PCB but It work for few minute and fail again. (I attached failure PCB picture below) (If I connect output of this amplifier directly to a high impedance horn speaker (don't use audio transformer), It work ok (but with 24V supply voltage, the speaker (high impedance, horn speaker) cannot operate at rated power)
Could you please recommend me a solution to this problem? any mistakes in my PCB? Is it correct when I use this design with that transformer to get a 70V line system ?