| 摘要 |
<p>PURPOSE:To prevent securely a microcomputer from malfunctioning even in case of a voltage drop by discharging a charge from a charged capacitor to the input of a constant voltage circuit when the input voltage of the constant voltage circuit drops below a reference input voltage. CONSTITUTION:When the voltage of an AC power source (e) drops temporarily owing to an external factor and the input voltage to the constant voltage IC1 drops below the lowest input voltage, the opposite-phase input voltage of a comparator IC2 rises above its in-phase input device and the output voltage of the comparator IC2 goes down to a low level to turn on a transistor(TR) Q3 and turns off a TR Q4. Consequently, the charged capacitor C3 is discharged to the input of the constant voltage IC2 and the input voltage of the constant voltage IC1 is held above the lowest input voltage, so that the output of the constant voltage IC1 maintains a rated output.</p> |
