| 摘要 |
The present invention provides a switching power supply which has an overcurrent protection characteristic with a small number of components. The switching power supply includes a regulator from a drain and an auxiliary winding VCC, a drain current detection circuit for detecting a current applied to a switching element, an oscillation circuit for outputting a clock signal of a constant frequency, a feedback signal control circuit for detecting a control signal from the secondary side and controlling current applied to the switching element, a clamping circuit for controlling the maximum value of current applied to the switching element, and a clamp voltage variable circuit for changing a clamp voltage of the clamping circuit and an oscillation frequency of the oscillation circuit according to a voltage of VCC.
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