| 摘要 |
PURPOSE:To put off the exhaustion of a battery and to obtain a backup circuit with less battery change, by connecting a battery for backup to a power source input terminal through a current counterflow preventive diode and by further connecting thereto an electrical double layer capacitor. CONSTITUTION:A power source 21 is connected to the power source input terminal of a device 23 necessary for power source backup through a current counterflow preventive diode 25, while in parallel thereto a battery 23 for backup is connected through a current counterflow preventive diode 26. Furthermore, to the same power source input terminal an electrical double layer capacitor 24 is set to connect. On this occasion, a capacitor 27 for removing ripple could also be connected. In this way, since the electrical double layer capacitor 24 is charged from the power source 21 in normalcy, the power is supplied from this electrical double layer capacitor 24 to the device 23 first of all in case of power interruption and the exhaustion of the battery 22 is thereby reduced. |
