Hello,
Until recently I had several failures of the integrated LM5118 in supply cards, designed in the same mode of the LM5118 Eval Board, without understanding what was the reason.
Previously I could not simulate the failure, because the cards were returned from the customers to be repaired, without understanding what the problem was. In this case in a card returned for repair, I found a short circuit between VCC and HB, sign that the internal diode was broken, so I understood where is the problem.
So as Garrett Roecker advised me in the last February 2017, I added a diode from VCC and HB of LM5118 and in this mode the LM5118 doesn't break anymore.
I noticed that the breaking happens in back mode with VIN>= 28V and a load of 2 Ohm near the short circuit, with the VOUT= 12.5V.
I note however that the added diode must be schottky, otherwise with the situation near of short circuit it will continue burning the internal.
In any case I want to thank the TI applications engineer Garrett Roecker, for the solution of the case.
Regards
Mario
