| 摘要 |
PROBLEM TO BE SOLVED: To curtail standby power requirement by materializing an intermittent operation where an ON period is short and an OFF period is long at the time of a light load, in simple circuit constitution and with its scale not being enlarged, in a switching power circuit. SOLUTION: A comparator OP1 compares the terminal voltage Vfb of an FB terminal, where the voltage level changes by the load state on the output side of a switching power source, with a reference level Vth to control the switching operation. Moreover, a parallel circuit composed of pull-up resistors R1 and R2 is connected to the FB terminal, and a switch element SW1 is connected in series to one pull-up resistor R2. Then, the switch element SW1 is switched on or switched off by the output of the comparator OP1 to switch the pull-up current of the FB terminal in conjunction with the change of the load state. COPYRIGHT: (C)2009,JPO&INPIT
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