A power control circuit includes a voltage output terminal, a control chip, a converter, and a comparator. A voltage input pin of the control chip is connected to a first power source. A voltage pin of the converter is connected to a second power source. A pulse input pin of the converter is connected to a pulse output pin of the control chip. An output pin of the converter is connected to the voltage output terminal. An inverting input terminal of a comparator is connected to a voltage output pin of the control chip. A non-inverting input terminal of the comparator is connected to the second power source through a first resistor and grounded through a second resistor. An output terminal of the comparator is connected to a detecting pin of the control chip and connected to the non-inverting input terminal of the comparator through a third resistor.