RCD 复位

Dissipative type Clamp/Reset technical Very low cost design of reset circuit with discrete components R, C and D Max. operating duty could be slightly higher than 50% (up to 55~65%), depending the magnetizing current reset by RC constant Critical point: Higher consumption because the energy storage on “C” should dissipates by passive component “R” The transformer volt/second balance should tradeoff by adjust the value of “C” and “R” for Clamp/Reset In case VDS ≤ 2Vin but very possible higher than 2VIN in worst case at open loop operating and max duty exceed 50% To avoid transformer saturation need to evaluate the Dset max of PWM in case of short circuit RCD reset

Forward Converter

The snubber capacitor voltage is fixed and almost independent of the input voltage, the MOSFET voltage stress can be reduced compared to the reset winding approach when the converter is operated with a wide input voltage range. Another advantage of RCD reset method is that it is possible to set the maximum duty ratio larger than 50% with relatively low voltage stress on MOSFET compared to auxiliary winding reset method, which results in reduced voltage stress on the secondary side. The maximum voltage stress the nominal snubber capacitor voltage