| 摘要 |
A switching power supply in which starting time is shortened, and its control circuit. A soft start circuit (20) is a circuit for soft starting a flyback system switching regulator and provided with two current sources, i.e. a first current source (220) and a second current source (222). The soft start circuit (20) comprises a second comparator (200) for comparing the feedback voltage Vfb of an output voltage with a predetermined threshold voltage Vth. If VfbVth, the second current source (222) is turned on together with the first current source (220) thus raising the soft start voltage Vss.
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