Electronic apparatus

Details Electronic apparatus Electronic apparatus

1990-12-07

1993-09-07

Popek, Joseph A.

Static information storage and retrieval

Powering

Data preservation

365228, 307 64, G11C 514, H03K 1724

Patent

active

052435776

ABSTRACT:
An electronic apparatus is provided with a main battery, semiconductor memories having a chip select input (active low), a backup battery, a pull-up resistor, a control unit for selecting one of the semiconductor memories, and a selection control line connected between the control unit and the chip select input. The selection control line is connected to the backup battery through the pull-up resistor. A switch for closing or opening the selection control line is connected between the selection control unit and the junction point of the control line and the pull-up resistor. A switch control unit is provided which controls the switch to open the control line when the semiconductor memory is powered by the backup battery. In another electronic apparatus having a detection circuit for detecting the voltage of the backup battery, the switch is closed only when the voltage is to be monitored.

REFERENCES:
patent: 4451742 (1984-05-01), Aswell
patent: 4777626 (1988-10-01), Matsushita et al.

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