VOLTAGE DETECTION CIRCUIT

PROBLEM TO BE SOLVED: To provide a detection circuit normally outputs a detection signal of a power supply voltage even if the power supply voltage is low or suddenly changed. SOLUTION: This circuit comprises a first reference voltage generation circuit 10A supplying the first reference voltage to a node N11A, a control voltage generation circuit 20 generating a control voltage at a node N12, a N-channel type MOS transistor Qn121 where a gate placed between a ground terminal and a node N13 is connected to a node N11A, and a P-channel type MOS transistor Qp121 where a gate placed between a power supply terminal and a node N13 is connected to N12. Since the circuit controls the P-channel type MOS transistor Qp121 by the control voltage and flows a current into the MOS transistor Qp121, the circuit can surely output a voltage detection signal VDTA through the node 13.