| 摘要 |
PROBLEM TO BE SOLVED: To protect circuit elements such as switching elements for rectification upon the occurrence of abnormality in the output from a transformer in the synchronous rectification circuit of a switching power supply. SOLUTION: In the synchronous rectification circuit, an abnormality detection circuit 14 detects abnormality in a trigger signal transmitted from a transformer T1. When an abnormality is detected by the abnormality detection circuit 14, an interruption circuit 15 interrupts the gate drive signal source of an NMOS transistor SW1 quickly. When an abnormality is detected by the abnormality detection circuit 14, a linear drive circuit 16 prevents the NMOS transistor SW1 from being turned off instantaneously while holding (clamping) the drain-source voltage of the NMOS transistor SW1 at a predetermined level. COPYRIGHT: (C)2007,JPO&INPIT
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