We have a problem with the LT8646S that keep on being destroyed and thereby making a short-cutting and therefore also destroying other components in the power supply. The LT8646S is used in a power supply for an RF PA stage for 80-800Mhz and it looks like it is destroyed only when turning the 56V DC external power off.
I have attached a circuit diagram that shows the connection of the LT8646S, the Diode i have set in with a Circle shows a workaround we have made to protect the LT8646S. Without this diode it is destroyed randomly after a number of power cykles.
The Power consumptions is approx. 2A.