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. 08, 1981
Filed:
Feb. 06, 1980
Andrew C Graham, Dallas, TX (US);
Mostek Corporation, Carrollton, TX (US);
Abstract
A battery backup circuit for an MOS memory which has a multiplexed pin (WE) that functions to provide backup power to a memory cell array (50) upon loss of primary power V.sub.cc. A voltage comparator (10) detects when the primary power V.sub.cc becomes less than the backup voltage on the WE terminal. Upon detection of loss of primary power the memory cell array (50) is powered by a connection to the WE terminal. A primary power status signal (POK) indicates the status of the primary power and is driven to a state indicating insufficient circuit voltage for normal operation when V.sub.cc drops below an acceptable limit or when there is inadequate substrate bias. The circuit of the present invention further generates an inhibit signal to prevent the operation of peripheral circuits (70) to write data into the memory cell array (50) upon detection of a failure of primary power. The inhibit signal is generated when primary power is lost or when the substrate bias is inadequate. A low-power auxiliary pump generator (92) provides a sufficient substrate bias to maintain the data pattern in the memory cell array (50) during the backup mode.