| 摘要 |
<p>PURPOSE:To prevent malfunctions of a device by providing a reset circuit consisting of a capacitor, a resistance, and a transistor TR in the reset terminal of a microcomputer to reset surely the microcomputer even when a momentary power failure occurs. CONSTITUTION:When a power source is turned on in the power-off state, a voltage supplied to a plus-side power supply terminal VDD of a microcomputer 1 rises in accordance with a power source Vc and reaches an operating voltage V1 of the microcomputer 1. When a capacitor C2 is charged after a certain time, the voltage of a reset terminal RST falls to the low level, and the microcomputer 1 performs the reset operation to start the normal operation. If a momentary power failure occurs in the power supply state, the voltage of the power supply terminal VDD is reduced to turn off a TR Tr1. The capacitor C2 is discharged quickly. When the voltage of the terminal VDD rises again, the microcomputer 1 performs the reset operation to start the operation similarly.</p> |
