| 摘要 |
PCT No. PCT/CH93/00225 Sec. 371 Date Dec. 8, 1994 Sec. 102(e) Date Dec. 8, 1994 PCT Filed Sep. 14, 1993 PCT Pub. No. WO95/02918 PCT Pub. Date Jan. 26, 1995In a synchronous rectifier having at least a transformer whose flow of current through the primary winding is periodically switched on and off and includes, as a controlled rectifier, a first and second MOSFET. A third and fourth MOSFET are provided whose source terminals are connected to the gate terminals of the first and second MOSFETs and to a second of two output terminals of the rectifier through a resistor. A Schottky diode is connected in parallel with the drain and source terminals of the first MOSFET with the cathode of the Schottky diode and the drain terminal of the first MOSFET being connected to a first of the two output terminals. A switching block circuit is connected between the parallel connection of the Schottky diode and the first MOSFET and the second output terminal of the rectifier. A capacitor is connected between the gate terminals of the third and fourth MOSFETs and the second output terminal of the rectifier. The output of a logic unit is connected in parallel with the capacitor. The logic unit receives an output from a switching block which output provides an indication of the current through the parallel connection of the Schottky diode and the first MOSFET. In the event of failure of current through the switching block, the logic unit provides a short across the capacitor resulting in a change from normal synchronous rectifier operation to a diode rectifier operation through the substrate diodes of the first and second MOSFETs.
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