PURPOSE:To obtain a small-sized, reliable control circuit device by packaging all circuits on one substrate, and outputting a fault detecting signal when one of reference voltage generating circuits is faulty. CONSTITUTION:Reference voltage generating circuits 41 and 45 are provided. The output voltage of the circuit 41 is used as a reference voltage of the 1st DC input voltage applied to a terminal. Then, the power voltage to a terminal 6 is stabilized by the output voltage VREF2 of the circuit 45, and the power voltage is divided through resistances to obtain reference voltages VREF3 and VREF4 of voltage comparators 52 and 53. Those comparators 52 and 53 detect the 2nd DC input voltage being higher than the voltage VREF3 and lower than the VREF4 respectively. Even if one of the circuits 41 and 45 enters into abnormal operation, a fault detecting signal appears at the output of the comparator 52 or 53, so all circuits are packaged on the same substrate to realize size reduction and high reliability.
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