LTC3780 : Back to square one, and now it works
After frying and fixing again the LCT3780 (feedback loop broken, one more time), i realized the current limiting is somehow flawed.  Here is the schematic of the original CC :     The problem is that the feedback (0.8v) is the sum of Isense and Vout * Pot  So the current limiting is not accurate and depends on Vout.   Let's change that, so that only one is used : Voltage or  Current mode.  It means the biggest of Vout or Isense is taken into account and the other one is ignored.   Biggest of 2 voltages:  it means diodes.   To do that we'll remove the 14k resistor on the board     And cut the track on the other side     (cut at the white mark )   Let's add a very small circuit instead :     We'll have a slight offset generated by the shottky diode (~ 200 mv in my case), but it's constant, it does not matter much.   That becomes (with the usual craftmanship):      The output of that small circuit will be connected to the pad of the 14k resistor we just removed  (the p...