Abstract: The apparatus of the present invention has an interface circuit which returns power in H-level output state, a first power circuit supplying a first supply voltage, and a second power circuit supplying a second supply voltage. The second power circuit receives the entered first supply voltage from the first power circuit, and in a first operation mode (L-level output condition), brings the first supply voltage of 3.3 V down to the second supply voltage of 1.5 V and supplies same to the interface circuit. In a second operation mode (H-level output condition) of the load circuit, a current output from the load circuit is brought up to the first supply voltage of 3.3 V and feeds same back to the first power circuit.