To prescribe so that an overall performance including external instruments or internal instruments agrees with a using purpose corresponding to the kind of a power source to be supplied.

This device 1 is so composed that two or more kinds of power sources are inputted selectively, and that a power source to be supplied V0 of a prescribed voltage generated based on the inputted power sources VBAT, VAD can be supplied to external instruments or internal instruments. In this case, the voltage of the power source to be supplied V0 is changed corresponding to the kind of the inputted power sources VBAT, VAD.