POWER-ON RESET CIRCUIT

PURPOSE:To improve the control accuracy of a power-on reset circuit by controlling qualitatively a voltage range subjected to power-on reset. CONSTITUTION:A 3rd transistor(TR) is provided in parallel with a 1st TR of an inverter comprising 1st, 2nd TRs and a bias potential divided by an impedance element is fed to the gate of the 3rd TR. Thus, even in the presence of the manufacture process, since the bias potential depends on the voltage division ratio of an impedance element, the dispersion is not almost affected. Concretely, assuming (1)-(4) as the potential of each node, then, when the level (2) divided by resistors R1, R2 is smaller than a threshold level of a TR 4, the Tr 4 is turned off and an output of a reset voltage control circuit 13 is in the reset state. When the level is higher than the threshold level, the TR 4 is turned on and a through-current flows between the TRs 4, 5 and the resistor R3, the output of the circuit 13 goes to a high level to wave the reset state.