Synchronous rectification controller boosts charger efficiency

February 02, 2015 // By Graham Prophet
Designed to provide a highly integrated, efficient and cost-effective solution for cell phone and similar portable electronic device chargers, Diodes Incorporated has introduced the APR343 synchronous rectification controller that integrates a secondary side MOSFET driver with an output voltage detection function to support a primary side control system.

This circuit configuration, using an external MOSFET for greater flexibility, allows for synchronous rectification in DCM (discontinuous conduction mode) operation by sensing the MOSFET drain-to-source voltage and providing a periodic signal to drive the MOSFET when the output voltage is lower than a certain threshold. By responding quickly to the secondary side voltage the APR343 can improve the transient response of the primary side control system and reduce the power dissipation of the secondary side rectifier.

Over-voltage protection and under-voltage lockout (UVLO) features are added to a design that minimises external components while saving board space with a SOT25 package. The APR343 is priced at $0.35 (1000).