Improvement of Reverse Recovery Characteristic in Synchronous Rectifiers Using a Bipolar Transistor Driven by a Current Transformer

Eiji SAKAI  Koosuke HARADA  

IEICE TRANSACTIONS on Communications   Vol.E75-B   No.11   pp.1179-1185
Publication Date: 1992/11/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Telecommunications Energy Systems and Switching Power Converters)
switching power converter,  synchronous rectifier,  offset voltage,  reverse recovery characteristic,  

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It has been reported that the efficiency of a low voltage power supply is improved by replacing diodes in an output-stage with synchronous rectifiers (SR). A SR consists of a bipolar junction transistor with a low-saturation voltage and a current transformer. Although the SR has low offset-voltage, its reverse recovery characteristic is usually poor. In this paper, an RCD circuit which improves the reverse recovery characteristic of the SR is proposed. This circuit is simple, and it is composed of a diode, a capacitor and a resistor. The analysis and the experimental results of the SR with the proposed RCD circuit are presented. The optimum design of the RCD to improve the reverse recovery characteristic of SR is discussed.