One or more first switches coupled to one of a primary transformer winding and a secondary transformer winding are controlled based on a first switch control reference clock signal. A reflected voltage across the other of the primary and secondary windings is sensed, and a second switch control reference clock signal is synchronized to the first switch control reference clock signal based on the reflected voltage. One or more second switches coupled to the other of the primary and secondary windings are controlled based on the second switch control reference clock signal. A digital isolator could instead be used to transfer a switch control reference signal across an isolation boundary. Switch control signals for controlling a set of switches on one side of the isolation boundary may be derived from a switch control reference signal that is synchronized with the transferred switch control reference clock signal.