| 摘要 |
PROBLEM TO BE SOLVED: To improve complexity brought to a circuit for generating a control signal of a switch of a synchronous rectifier circuit of a DC-DC converter. SOLUTION: A bridge inverter circuit is formed of a first to fourth switches Q1 to Q4 and a transformer T. The synchronous rectifier circuit consisting of a fifth and sixth switches Q5, Q6 is mounted to a secondary winding N2 of the transformer T. A filter circuit 4 of choke-input is mounted at the output step of the synchronous rectifier circuit. For generating control signals of the first to sixth switches Q1 to Q6, there are mounted a sawtooth generator, a means for generating a signal that indicates the amplitude value Vp of the sawtooth, a means for generating 0.5Vp that indicates half the amplitude value Vp, a means for generating a first pulse-width indicating value V1 in the range of 0 to 0.5Vp, a means for generating a second pulse-width indicating value V2 by computing Vp-V1, a first and second comparators for comparing the sawtooth and the first and second pulse-width indicating values V1, V2 and a third comparator for comparing the sawtooth and 0.5Vp. The control signals Q1 to Q4 of the first to fourth switches are generated by the outputs of the first and second comparators, and the control signals of the fifth and sixth switches Q5, Q6 are generated by the output of the third comparator.
|
