Dear Tech Support,
I built up a stand-alone TDA7269A audio amp brd using one of the circuit app's of the data sheet. It worked well - clean, balanced, and the channels are independent of each other. So, I rolled the same design onto an integrated system board with a power supply and and separate signal conditioning for each of the inputs. I now get completely different (bad) behavior responses of the amp. I have verified the circuit design and the PCB layout, tried the 2 single-supply app's noted in the App Notes plus one not listed, and exhausted all the clean-up techniques I can think of.
The behaviors I'm getting include:
- Unbalanced output
- Significant output signal mixing - change the input on Ch1 and Ch2 responds. I also get increased output when I turn both inputs up like an adding function
- Get significant waveform distortion
- A strange behavior where as I increase the input level on one channel, it causes it cause the output(s) to increase, then fade to zero, then increase again. It's useless!
I would be happy to provide a screen shot of the schematic if you are interested in seeing the differences between the stand-alone amp and the integrated amp.
Best regards and out of ideas,
David
