Synchronous rectifiers for portable chargers promise improved efficiency

March 05, 2015 // By Graham Prophet
APR3415 and APR34330 are synchronous rectifiers that combine a driver circuit with an internal MOSFET to provide cost effective rectification with reduced power dissipation and use of fewer external components.

Target applications include adapters/chargers for portable consumer products and home appliances. The devices 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 optimised drive signal using fewer external components. The internal N-channel MOSFET has been optimised 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 comes 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.

APR3415 is priced at $0.40 and APR34330 at $0.38 (1000).

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