The final TEC board is done and appears to work great. This is the same circuit as my prototype, with the test jumpers removed. I need four channels for the different parts of the laser, and I fit all four on one board. I needed to make the board larger for this, and have settled on a standard board size of 172mm X 85mm. This insets nicely with standard audio amplifier heat sinks. I’ve also decided to keep the IO header in a consistent position for all boards, so it will be easy to run a single ribbon to them. They are designed to all take the same IO connector so the boards can be daisy-chained.
Final TEC controller board
One minor tweak on this board was to change the digital power supply from a switch mode supply to an LDO regulator. The prototype current usage of the controller chips turned out to be very small.