I am designing a snubber circuit for my buck converter. I am following the procedures mentioned in the attached application note. When I do the procedure mentioned on page 3, step 2 where it says to connect a capacitor, a 1nF, 100V 0603 ceramic cap in my case, the low side mosfet (SIR882BDP-T1-RE3) heated and eventually blew up. The test conditions were as follows: Vin=80V, Vout 12V, Iout=1.7A, fsw=180kHz.
I am attaching an image of Vds waveform of low side FET without snubber, there is an overshoot of about 120V, which is higher than the rated value, but for some reason, it didn't blow up before.
I'll be taking into account the DC bias of the capacitor during calculations and using a ground lead adaptor as mentioned in the note.
Do let me know how I should proceed with the design.