I'm using this chip in some application for auxiliary supply without galvanic isolation.
In this application the input is a 16-32Vdc (railway supply), and 3 sets of LMR14020 to generate: 12V@0,2A (mos gate supply), 5V@0,2A (service USB port), and 3,3V@0,8A (microcontroller).
Never found any issue at bench, but meet some return from the field: I find the LMR on 3,3V destroyed (upper case out) and all chips under 3,3V to be changed.
To the original scheme we had added one more 22uF cap, and a stronger 33V tranzorb to ensure the input. It seemed like a good solution that worked.
Now I have a new return with the same issue, for the first time with scheme modification applied.
Where I have to investigate? Do you have any similar case?
How can the chip cover be damaged? Overvoltage (but the tranzorb should work fine)? Overcurrent (but internal limitation should protect)? Overtemperature (but internal protection should work)?
Thanks