| 摘要 |
PURPOSE:To reduce the burden of a storage holding battery to reduce expenses of maintenance by supplying power to a volatile memory from an external electric power source when the external power source can be used and providing a mechanism which cuts off power from the storage holding battery during this power supply. CONSTITUTION:The current inputted from an input terminal 9 of an external auxiliary power source 8 is converted to 3-5V DC voltage by a rectifying circuit 8a and is applied to a CMOS memory array 2 in a CMOS memory cassette 1 from an output terminal 11 through a diode 10. A storage holding battery 4 is connected to the output terminal 11 through a diode 12. Since the voltage of the storage holding battery 4 is 2-3V and is lower than the voltage of the external power source by about 1V, a backward voltage is applied to the diode 12 to cut off the current of the storage holding battery 4. Consequently, when the external power source can be used, power is kept without the storage holding battery 4. Thus, the burden of the storage holding battery and expenses of maintenance are reduced. |
