Hi lok,

In the buck converter, the synchronous MOSFET only has reverse recovery losses (as it does not conduct in forward mode). Many of our older generation 3 discrete device models are missing reverse recovery losses, and so when used in the synchronous position, they will report 0 W switching losses. Here is a comparison of one of our newest devices to an old one:

While these losses are small, we recognize that this is a model limitation. If you have specific parts that you need reverse recovery losses for, let us know and we will do our best to get you updated versions of those models.

One other note, if the simulated reverse recovery losses are less than 0.005 W, they will also be reported as zero even though the losses are in the model.

Thanks,
Blake