The Raspberry PI 5 (RPi5 from now on) is the latest (at the time of writing) SBC from the Raspberry Pi foundation. It’s a set up in functionality from its predecessors, but it has a couple of things which might be problematic for some:
So I figured I kill both of these birds with one stone, by designing a single board which would provide 5V/5A to the RPi5 and incorporate a Class D audio amplifier to drive loudspeakers directly. It all fits on a Pi Zero sized board, which has the advantage that it doesn’t cover the RPi5 completely, allowing better convection away from the main board.
After a couple of experiments, I settled on the TPS56637 as a power supply - it’s a synchronous buck converter, runs at up to 28V in, and is specified for 6A continuous output - all from a package which is 3mm on each side.
Sticking with TI, the TAS5731 is a decent Class D amplifier, providing up to 20W/channel and operating on a power supply of up to 21V. It’ll drive two speakers in bridge mode.
I went for a four-layer board: the extra copper in the inner layers helps to spread heat away from the chips on the board, the added cost is minimal and routing’s a breeze.
Minus connectors, here’s how it ended up:
… and here’s how it arrived.
Next: stress testing. Time to load it up with resistors and see how hot it gets.