Reason for LT8315 failure along with output capacitor

Hi,

I am using LT8315 as a buck converter for converting 363V to 15V @0.2A.IC is worked fine.

Recently we had the failure in LT8315 with controller which shows burnt mark.

The output capacitor also burnt and impedance is measured as short.

The impedance across the IC pin 1(drain) and pin 20(ground) is measured as open.

Can you suggest the reason for failure in LT8315.

With regards,PDFPDF

P.Selvam.