Patent ID: 7088084

Claim:
A power supply circuit comprising: a voltage source whose one end is connected to a reference voltage node, the voltage source having a first output node; a voltage control circuit which receives a voltage of the first output node, the voltage control circuit having a second output node, and changing voltages of n (n being a positive integer of 2 or more) different values according to control signals to output them to the second output node; a first switch element connected between the second output node and the reference voltage node; a second switch element connected between the first output node and the second output node; and a switch control circuit which controls the first switch element so as to be conductive when the voltage control circuit changes the voltage of the second output node from a first voltage to a second voltage that is lower than the first voltage, and which controls the second switch element so as to be conductive when the voltage control circuit changes the voltage of the second output node from the second voltage to the first voltage.