Patent ID: 8653872

Claim:
A reset circuit of a microcomputer to which a drive voltage is supplied from a switching power circuit that executes feedback control to stabilize a positive first rectified voltage generated by rectifying an output voltage of a switching transformer, comprising: a reset IC (Integrated Circuit) that has: a reset signal output terminal that is connected to a reset terminal of the microcomputer that is driven by a constant voltage generated by regulating the first rectified voltage by a regulator, and a voltage detection terminal that inputs the constant voltage thorough a first register, and outputs a reset signal to the microcomputer when an input voltage input to the voltage detection terminal is lower than a predetermined value, an NPN type transistor in which a collector is connected to the voltage detection terminal through a second resistor and an emitter is connected to the ground, and the transistor is turned on when an output voltage of the switching transformer is lower than a predetermined level, wherein the voltage lower than the predetermined value is input to the voltage detection terminal when the transistor is turned on, and the voltage equal to or higher than the predetermined value is input to the voltage detection terminal when the transistor is turned off.