The RCD turn-off snubber is intended to control the rise of voltage rate on the mosfet in order to minimize switching losses during turn-off transitions.
When turn-off occurs the snubber capacitor gets charged through the snubber diode, thus determining the rate of rise of voltage across the mosfet. Since switching losses are depending on current-voltage overlapping, by delaying the voltage to rise after the current had already risen we can achieve minor losses. During turn-on the capacitor gets discharged via the snubber resistor to the initial conditions.
For detailed circuit analysis and design CALCULATOR visit:
http://j.gs/5535160/rcd-turn-off
