Synchronous rectification is being used to improve performance in an increasing number of ac/dc power supply applications, as tougher ecodesign targets drive designers to achieve further gains in energy efficiency. For optimum efficiency, cost, and reliability, an economical solution is needed to control the synchronous rectifier MOSFETs without allowing reverse current to flow during turn-off. As power supply designers seek further improvement in efficiency, more and more are choosing to use a synchronous rectifier in place of the traditional high-speed or Schottky diode in flyback or forward converters, as shown in Fig. 1. This requires control of the MOSFETs (synchronous rectifier MOSFET for both Forward and Freewheeling), to turn the device on and off at the correct times to maintain the flow of current through the load.
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