| 摘要 |
PROBLEM TO BE SOLVED: To provide a new synchronous rectification driving circuit that makes it difficult for a back current to flow. SOLUTION: In the synchronous rectification driving circuit, with its primary and secondary sides isolated with a transformer T, a main switch Q1 is provided on the primary side, a rectifying switch Q2 and a commutation switch Q3 on the secondary side, and a smoothing circuit between a choke L1 and a smoothing capacitor C1 provided to the output section. The commutation switch consists of a MOSFET, dividing resistors R1, R2 are connected between the output terminal of the choke and the source electrode of the commutation switch, the connecting point of these dividing resistors is connected to the gate terminal of the commutation switch, the source-drain electrode of an auxiliary switch Q4 is connected between the source-gate electrode of the commutation switch, and the gate signal of the auxiliary switch is so controlled as to be reversal to the gate signal of the main switch. COPYRIGHT: (C)2007,JPO&INPIT
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