Patent ID: 7777993

Claim:
A wiper control circuit, comprising: a first connection terminal for connecting one end of a variable resistor to a ground via a switching element, the other end of the variable resistor in an external circuit being connected to one end of an operation switch to be turned on and off in accordance with a specified operation instruction, wherein a resistance value of the variable resistor changes according to an instruction to set an interrupt time for causing an interrupt operation of a wiper installed in a vehicle, a second connection terminal for the connection to the other end of the operation switch; a third connection terminal for receiving a first power supply voltage; a power supply for outputting a second power supply voltage lower than the first power supply voltage based on the first power supply voltage received by the third connection terminal; a first diode disposed between the first connection terminal and the power supply in a reverse direction when seen from the first connection terminal; a first voltage detecting portion for detecting an anode voltage of the first diode, the upper limit of whose permissible range of voltages to be detected is lower than the first power supply voltage; an operation instruction detecting voltage supplying portion for supplying the first power supply voltage received by the third connection terminal to the second connection terminal; and a second voltage detecting portion for detecting a terminal voltage of the second connection terminal.