I use the LTC3554. I switch it On with a High on PWR_ON and OFF with Low at this PIN. With my first Boards I have no Problems. With the Production Boards from a other manufacture the LTC3554 didn’t switch On with a High at PWR_ON.
On/Off with the ON-Pin is OK on both Boards.
The wiring at the LTC3554 is on both Boards the same.
The marking on the LTC3554 is different:
Have you some Idea what was wrong ?