| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide the synchronous circuit of a small, inexpensive and insulating switching power supply excellent in high speed operation, and to provide a switching power supply. <P>SOLUTION: When the control IC1 of a switching power supply 10 controls conduction state of a switch element Q1 based on a PWM drive signal being supplied from the control IC1, a voltage having an effective value dependent on the duty ratio of the PWM drive signal is derived from the secondary circuit of a transformer T1. Similarly, when the control IC2 of a switching power supply 20 controls conduction state of a switch element Q2 based on a PWM drive signal being supplied from the control IC2, a voltage having an effective value dependent on the duty ratio of the PWM drive signal is derived from the secondary circuit of a transformer T2. In this regard, the control IC2 supplies the PWM drive signal to the switch element Q2 in synchronism with a sync signal being supplied from the control IC1 through a transformer T3 under insulated state. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
