| 摘要 |
<p>PURPOSE:To prevent malfunction of a device by providing a discharge resistor of an electric charge of a capacitor via a diode to a voltage dividing point of a voltage dividing resistor of a transistor (TR) connected to a reset terminal of a microcomputer to ensure the reset operation. CONSTITUTION:When a momentary power failure takes place after power is applied, a voltage of a positive power terminal VDD of a microcomputer 1 is dropped and a TR is turned off at a prescribed time. Then the electric charge charged in a capacitor C1 is discharged via a voltage dividing resistor R3 and most of the charge is discharged rapidly via a discharge resistor R4 and a voltage dividing resistor R6 through a diode D1. On the other hand, since the voltage RST at the reset terminal is decreased according to the power supply Vc since the TR is turned off at a prescribed time. When the voltage of the positive power terminal VDD rises again, the circuit is brought into a similar state when the power is applied from the power interruption, the microcomputer 1 is reset surely and the normal operation is started.</p> |
