| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption at stand-by state in a switching power supply 1 as a single body for driving a load, constituted of a drive circuit 6 as a power load and its control circuit 8. SOLUTION: Continuous pulses are generated from an output PON of a control circuit 8 in a normal operation state and are integrated by C8, R9, and C7 to turn TR5 on and turn FETTR4 off. Then, a shunt regulator 9 drives D3 of PC according to the output voltage VM. In the sand-by state, the operation of control circuit 8 is stopped to turn TR5 off and turn FETTR4 on, so that D3 is always lightened and changed into an oscillation stop state. When VM is lowered by the consumption of D3, the FETTR4 is turned on to keep a minimum voltage. In this way, the VM at stand-by states requires only a voltage for keeping the D3 in a normal lightened state and in an intermittent oscillation state, and the power consumption at stand-by state can be reduced. COPYRIGHT: (C)2003,JPO
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