In a previous note I’ve designed a replacement controller for the Ricor K526S cryocooler. In this note I describe a PCB I designed that fits into the original case.
The schematics is simple:
I’ve used 10A MOSFETs, and high-side MOSFET drivers on every channel to make sure the low-side FETs conduct as well as the high-side ones. It’s actually overkill in both cases: the motor shouldn’t consume more than 3 A and Vgs of 5 V should be sufficient to supply exactly 3A, but I remember the original driver heating up a lot when the rotor wasn’t spinning well, and so I decided to add this safety factor.
The board turned out quite elaborate:
The BOM is as follows:
The design files are TBD.
The gateware differs from the previously developed one as it supports self-test (when TP1 is pulled high):