| 摘要 |
PURPOSE:To perform backup operation correctly and to prolong the life of a charged type battery by comparing the terminal voltage of the charged type battery with a reference voltage and disconnecting the charged type battery from a memory when the terminal voltage is lower than the reference voltage. CONSTITUTION:A reference voltage source 15 generates and supplies the specific reference voltage Vs to a comparator 16. The terminal voltage VB of the charged type battery 12 is supplied to one input terminal of the comparator 16. The comparator 16 once detecting the terminal voltage VB of the charged type battery 12 dropping below the reference voltage Vs generates a control signal Sc at its output terminal to energize the coil 19 of a relay circuit 17, and breaks the relay contact 18 a specific time later to disconnect the charged type battery 12 from a backup power source while connecting a stand-by backup battery. Consequently, the disconnection of the charged type battery 12 and the connection of the stand-by backup battery are carried out automatically without the intervention of an operator. Further, it is possible to let the operator know that through a warning circuit. |
