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:
Nov. 17, 1998
Filed:
Nov. 22, 1996
Timothy Don Davis, Arlington, TX (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A circuit for power arbitration, low battery voltage detection, and the operation of battery backed circuitry for systems in which the system power supply voltage range overlaps that of a battery source. A voltage regulator is used to regulate the battery voltage so that the voltage range of the battery source is below the voltage range of the system supply. The regulator is based on a silicon-bandgap referenced methodology and consumes an insignificant amount of current so that the battery life is not appreciably affected. The regulator also has a smaller variation in its output voltage than the battery. A temperature and supply voltage compensated voltage is produced by the combination of a subthreshold current source, parasitic bipolar devices, and voltage buffering, and used to provide a voltage source for the battery backed circuitry of the system. The regulated voltage is set to a value lower than the system supply and serves as the battery supply input for the power arbitration circuitry. The regulated voltage permits the internal power arbitration scheme of the present invention to be equivalent to existing arbitration circuits even though the battery and system supply voltage ranges overlap.