| 摘要 |
A switching power supply with the increased efficiency at light load has a switching power circuit, a power monitoring circuit and a light load power supplying circuit. The switching power circuit converts an AC power to a stable DC power and sends the DC power to a load according to voltage variation of the load. When the power monitoring circuit detects the AC power and determines that the load is in a light state, the power monitoring circuit controls the light load power supplying circuit to output a small-power DC to the load. As the DC power provided by the light load power supplying circuit is small, the switching loss ratio is lower in its light load state. Therefore, the operating efficiency at the light load state is higher.
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