| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a microcomputer reset circuit which can improve the response performance of a timer switch. SOLUTION: The charging voltage of an electrolytic capacitor C20 is supplied as the source voltage VD of a microcomputer IC20 to the microcomputer IC20. An integrating circuit composed of a resistance R20 and a capacitor C21 integrates the source voltage, which is applied to a positive-polarity input terminal of an operational amplifier IC21 designed on the assumption of use of a single power source. The source voltage is divided by resistances R26 and R27 and applied to a negative-polarity input terminal of the operational amplifier IC21. Even when the source voltage falls, the 'H' output of a voltage which is 1 to 3 V lower than the source voltage is generated by the operational amplifier IC21. This output is supplied to a reset terminal/RESET and then when the power source falls, a reset condition is met right after the source voltage falls. Consequently, resetting is completed in a short time and the time needed to raise the source voltage again can be shortened to quicken the response of a switch.</p> |
