| 摘要 |
<p>PROBLEM TO BE SOLVED: To extend the life of backup battery by charging an electrolytic capacitor which serves as an auxiliary power supply at the time of a backup operation up to a value between the voltage of main power supply and the voltage of backup battery. SOLUTION: An electrolytic capacitor 22 which serves as an auxiliary power supply at the time of a backup operation and diodes 15 and 16 are added to a conventional circuit. When main power supply is on, the condenser 22 is charged to be almost the same voltage with power supply + B1 through the diode 15 from power supply + B. After the main power supply is turned off, because the charging voltage of the copacitor 22 is higher than the voltage of battery 12, the power supply Vcc of a microcomputer 11 is supplied through the diode 16 from the capacitor 22. When the condenser 22 discharges and charging voltage falls to be lower than the voltage of the battery 12, diode 14 is turned on and the diode 16 is turned off. Therefore the power supply Vcc of the microcomputer 11 is supplied via the diode 14 from the battery 12.</p> |
