| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply capable of reducing power loss in a queuing mode. SOLUTION: A switching power supply feeds pulsating currents, obtained by rectifying commercial AC power, to a transformer intermittently by a transistor. It rectifies and smoothes the output of the transformer to generate a first DC output voltage V1, and also has a regulator that generates a second DC output voltage V2 which is more stable than the first DC output voltage V1. In the energy-saving mode that is achieved when a control signal SLP is H level, a second voltage detecting circuit is operating and repeatedly sends operation or non-operation signals to a PWM circuit, in such a way that the first DC output voltage V1 changes between threshold Vth1 and Vth2 to cause the transistor and PWM circuit to operate intermittently. A second DC output voltage V2 outputs a stable voltage, irrespective of the modes.
|
