Synchronous rectifiers enable highly-integrated and efficient portable chargers

Addressing the need for higher integration and efficiency in portable chargers, Diodes Incorporated has introduced two synchronous rectifiers: the APR3415 and APR34330. These devices combine a driver circuit with an internal MOSFET to provide cost effective rectification with reduced power dissipation and using fewer external components. Target applications include adapters/chargers for cellular and cordless phones, ADSL modems, MP3 players, and similar portable consumer products and home appliances. The APR3415 and APR34330 are synchronous rectification switchers for 5V output-voltage applications operating in discontinuous conduction mode. Synchronous rectification can reduce secondary-side power dissipation, while the devices’ ability to sense the MOSFET drain-to-source voltage enables an optimized drive signal using fewer external components. The internal N-channel MOSFET has been optimized for low gate charge, low RDS(ON), fast switching speed and reverse recovery, which helps these devices provide a fast response to secondary-side voltage and can also improve the transient performance of a primary-side control system. The APR3415 is aimed at designs requiring output currents up to 2A and is supplied in a standard SO-8 package. The APR34330 is intended for output currents up to 1.5A and is offered in an SO 8EP exposed-pad package. Both devices feature over-voltage protection (OVP) and VCC under voltage lock out, which is not typically available on competitive devices. This not only aids system safety and reliability, but also extends their use in additional application areas, such as standby and auxiliary power supplies, says the company.