Control of switching devices in synchronized-rectification system

摘要

A DC-DC converter comprises a switching pulse generator for generating a plurality of switching pulse signals for operating a primary switch and a synchronized-rectifying circuit. The switching pulse generator generates the respective switching pulse signals having different pulse widths based on different control voltages which are generated by a voltage divider comprising a variable-impedance device. The pulse width of each switching pulse signal is set according to the differences between the control voltages. The switching pulse generator comprises a first control circuit for the primary switch and a second control circuit for the synchronized-rectifying circuit. Switching timing of the synchronized-rectifying circuit is deviated from that of the primary switch by a period corresponding to the difference between a certain control voltage and each of the other control voltages.