...
^ No load
...
^ 1A Load
...
^ 2A Load
Power Validation Part 2
I replaced the LTC6820 ICs and am now getting a 0.22V on the 3V3 rail. They seem to be drawing too much current or causing a short. When not powered, the 3V3 line does not show any signs of a short, has about 170k of resistance to GND, whether or not the controller board is in place - this test was done measuring between the 3V3 and GND connections on P7, which it turns out is not correct. The GND that is labelled on this connector on the rear (which I assumed was the board GND) goes through the HV relay activation FET before going to board GND. So I was never measuring the real GND point when measuring this resistance. A careful look through the schematics would have revealed that, but fixing the silkscreen to not show GND might also be a good idea. Measuring between the GND test point on the right side of the board and 3V3 indicates about 1Ohm of resistance → so we found an issue - likely from the isoSPI ICs.
I double checked the pin assignment and layout for the LTC6820 ICs and it all seems good.
So my conclusion is busted ICs, likely due to the original plugging the board in backwards. We will order some extras and test it out.
Now I need another working controller board to complete the validation.