Does the body diode of the high side n-channel FET in a buck converter turn on during switch node voltage spike time?
I think I know why.

When the high side FET is on, the body diode is effectively shorted by the channel, taking it out of the equation.

https://e2e.ti.com/support/power-management/f/power-management-forum/842123/csd18510q5b-body-diode-clamping-behavior-for-switch-node

There are parasitic inductance even from the source of the high side FET to the switch node, hence the reason why VSW ring so high but there is no catastrophic damage from the VSW to VIN path. The path from VSW to VIN is more than just the RDSon of the high side FET.


Thanks and have a nice day.