A few posts ago I mentioned that I was having trouble with my Class-D amplifier design. It’s been sitting on the shelf for a few weeks and I think it’s time to have another look at it.
It’s amazing how you can notice new things when you take a fresh look at something. The problem is obvious now. I was missing a ground trace which introduced some noise into the input. Also the input impedance was way too high which made the amp very sensitive to that noise. The result was some nasty buzzing and it had nothing to do with the power supply as I first thought.
So now it’s working. Yay! I also upgraded it to the Texas Instruments TPA3110 which is completely pin-compatible and has 15 Watts of power. My ears are suitably hurting after running some tests at full volume and it didn’t even get warm.
So next I need to correct the PCB in light of these changes and it is done.