Patent ID: 8629630

Claim:
A control circuit, adapted to control a power converting circuit for stabilizing an output of the power converting circuit, the control circuit comprising: a capacitor; a charging unit having a first current source coupled to the capacitor for charging the capacitor; a discharging unit coupled to the capacitor for discharging the capacitor; a feedback control unit controlling the charging unit to charge the capacitor according to a feedback signal representing the output of the converting circuit; a duty-cycle adjusting unit generating a control signal, and adjusting a duty cycle of the control signal according to a voltage of the capacitor, wherein the charging unit has a first switch coupled between the first current source and the capacitor, the feedback control unit has a comparator, and the comparator controls the first switch to be conducted or cut off according to the feedback signal and a reference voltage signal; and a protecting unit, generating a protecting signal to have the duty-cycle adjusting unit to stop outputting the control signal when a level of the feedback signal is lower than a first protecting value, or the level of the feedback signal is lower than the first protecting value for a predetermined time period.