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:
Jan. 08, 1985
Filed:
Jul. 18, 1983
Raymond O Colbert, Oaklandon, IN (US);
Bengt H Hellman, Indianapolis, IN (US);
AT&T Bell Laboratories, Murray Hill, NJ (US);
Abstract
In an electrical circuit where power supply interruptions may cause significant adverse consequences, a secondary battery is often used to maintain power when the load voltage falls below a predetermined threshold. MOS transistors interconnect primary and secondary voltage supplies with the load. A sequence control circuit assures that only one MOS transistor is on at any time. In one embodiment of the invention, different time constants cause all MOS transistors to turn off before changing voltage supplies. In another embodiment of the invention, voltage comparators, each having a different threshold, cause all MOS transistors to turn off before changing voltage supplies. A capacitor maintains the load voltage during switching and positive feedback assures that the switching interval is brief. This arrangement is particularly advantageous in low power applications utilizing one or more lithium batteries.