| 摘要 |
In a switching power source apparatus which outputs a DC output voltage converted from a DC power source voltage, the DC output voltage is compared with a reference voltage to generate a feedback signal which decreases as the DC output voltage increases. A current detecting signal which decreases as the output current increases is also generated. The smaller one of the feedback signal and the current detecting signal as a comparison signal is compared with a triangular signal in a PWM comparator to produce a PWM signal. A semiconductor switch is on-off controlled by the PWM signal. Therefore, the apparatus can perform a constant voltage control with a current limit function, which can improve the accuracy of a current limit operation, eliminate the need of a special high speed operation of a current detecting circuit and a driver and stabilize the output voltage during the operation of current limit.
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