The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 07, 1993
Filed:
Dec. 07, 1990
Sharp Kabushiki Kaisha, Osaka, JP;
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.