A power control circuit includes a power switch unit operable so as to enable and disable supply of an input voltage from an external power source to an LC circuit, a voltage detecting unit for generating a first voltage signal in accordance with an output voltage applied to a load and outputted by the LC circuit, and a current detecting unit for generating a second voltage signal in accordance with a current flowing through the power switch unit. A driver receives a pulse width modulation signal from a comparator in accordance with a comparison result between a summation of the first and second voltage signals and a reference voltage, and outputs a driving signal to a control input unit of the power switch unit so as to control a duty cycle of the power switch unit, thereby controlling rated power supplied to the load to correspond to the reference voltage.