In summary, synchronous rectification is used to improve the efficiency of the rectification, replacing diodes with an active controlled switch. The diode voltage drop causes power losses in the rectifying diode and can be reduced by replacing it with a switch, typically a MOSFET. NXP’s GreenChip SR is a control IC which operates on the secondary side of the transformer in a flyback converter and drives a synchronous rectification switch resulting in high power supply efficiency and performance. There are also GreenChip SR versions available that also measure the output voltage, control the feedback loop, and offer protection against high output currents.