Design of smart power synchronous rectifier

In low-output-voltage DC/DC power converters, power losses due to the conduction of rectifying devices are significant. Using synchronous rectifiers instead of the conventional fast recovery diodes or Schottky diodes is an effective solution to this problem in most topologies. However, for synchronous rectifiers to perform effectively, this requires an external gate drive with proper sensing and timing control circuits. This can increase the complexity and cost in power converter hardware implementation. For the first time, a smart power synchronous rectifier (SPSR), which is a two-terminal MOS rectifier, is designed to overcome this difficulty. The SPSR integrates a simple control unit with a power MOSFET into a smart module to form a self-controlled synchronous rectifier. It has great advantages over the conventional discrete circuit composition, such as integrated gate control, precise timing switching and fast transient response, which are suitable for applications in high-frequency pulsewidth modulation (PWM) power converter circuits.