| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that a ZVS operation of a switch Q1 is performed using free vibration of an inductor L1 for smoothing output current, however, time to the ZVS operation becomes long making difficult to realize high frequency, and a timing control circuit also becomes complicated in a conventional switching power supply. <P>SOLUTION: The switch Q1 and a switch Q2 are serially connected to input current Vin, and power is supplied to a load 3 through a serial circuit between the inductor L1 which is for smoothing the output current and an inductor L0 with smaller inductance value than that of the inductor L1 from connection points of them. A diode FD and a bootstrap capacitor C1 are connected to the connection points of the inductor L1 and the inductor L0. In a light load, when current is flown to the inductor L0 via the bootstrap capacitor C1 by turning the switch Q2 on for predetermined time just before turning the switch Q1 on, and the switch Q2 is turned off after that, input side potential of the inductor L0 rapidly rises by self-induction electromotive force to certainly perform the ZVS operation of the switch Q1. <P>COPYRIGHT: (C)2012,JPO&INPIT |
