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DC-DC flyback converter having a synchronous rectification self-driven circuit

  • US 7,791,903 B2
  • Filed: 11/21/2006
  • Issued: 09/07/2010
  • Est. Priority Date: 11/28/2005
  • Status: Active Grant
First Claim
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1. A DC-DC flyback converter, which comprises:

  • a three-winding transformer;

    a primary power circuit including a first MOSFET connected to a first winding of the transformer;

    a secondary power circuit connected to a second winding of the transformer, the secondary power circuit further including a synchronous rectifier comprising a second MOSFET having first and second output terminals; and

    a self-driven circuit including connected to a third winding of the transformer, wherein the self-driven circuit further includes a negative voltage removal circuit for removing negative voltage between the output terminals of the synchronous rectifier and a synchronous rectifier trigger switch-off circuit for switching the synchronous rectifier to an off condition, wherein the negative voltage removal circuit is formed by a third MOSFET and a resistor, while the synchronous rectifier trigger switch-off circuit includes the third MOSFET, the second winding of the transformer and a Zener diode.

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