Patent ID: 7167028

Claim:
A voltage detection circuit comprising: a first smoothing capacitor connected between an output terminal on the high potential side and an output terminal on the low potential side; first and second resistors connected in series to each other between the output terminal on the high potential side and the output terminal on the low potential side; an error amplifier which amplifies an error voltage between a first voltage, which is determined by dividing a desired voltage between the output terminal on the high potential side and the output terminal on the low potential side by means of the first and second resistors, and a second voltage, which is determined by dividing an actual voltage between the output terminal on the high potential side and the output terminal on the low potential side by means of the first and second resistors, and which outputs the error voltage amplified; a regulator which outputs a steady potential to a reference voltage terminal when a high potential is supplied to the output terminal on the high potential side; a second capacitor connected between the reference voltage terminal and the output terminal on the low potential side; a current mirror circuit which has a first switching element whose control terminal is connected to the output terminal of the error amplifier and which has a first constant current source connected between the reference voltage terminal and the terminal on the high potential side of the first switching element and which feeds a current, which is predetermined times larger than a current which flows from the first constant current source, into a detected signal output terminal according to the state of the first switching element; a switching element for starting connected between the reference voltage terminal and the control terminal of the first switching element; and a start-stop circuit which brings the switching element for starting to an OFF state when the potential at the reference voltage terminal is higher than or equal to a predetermined starting potential and which brings the switching element for starting to an ON state when the potential at the reference voltage terminal is less than the predetermined starting potential.