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:
Dec. 03, 1996
Filed:
Aug. 08, 1995
Robert A Mammano, Costa Mesa, CA (US);
Larry Wofford, Cary, NC (US);
Winthrop H McClure, Londonderry, NH (US);
Burt L Price, Apex, NC (US);
Unitrode Corporation, Merrimack, NH (US);
Abstract
A battery protector for providing overvoltage and undervoltage protection to one or more series-connected cells. The battery protector includes a voltage detection and comparison circuit, providing an overvoltage signal indicative of whether the voltage across any of the cells is greater than an overvoltage threshold level and an undervoltage signal indicative of whether the voltage across any of the cells is less than an undervoltage threshold level, and a switch connected in series with the current path between the cells and a charger and/or load. In one embodiment, the switch is a four-terminal FET and a bias control circuit is provided for selectively connecting the body region of the FET to ensure that current does not flow through the parasitic FET diodes. A second control circuit responsive to the overvoltage and undervoltage signals controls conduction of the switch, causing the switch to close if any of the following conditions occur: (1) the overvoltage and undervoltage signals do not indicate an overvoltage or undervoltage condition, respectively; (2) the overvoltage signal indicates an overvoltage condition, but the cells are attempting to discharge; or (3) the undervoltage signal indicates an undervoltage condition, but the charger is attempting to charge the cells.