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. 23, 1996
Filed:
Jun. 21, 1993
Gerald L Brainard, San Jose, CA (US);
AST Research, Inc., Irvine, CA (US);
Abstract
A battery charging system is disclosed that includes an efficient switch mode power supply, multiple linear current limiters, and feedback means to allow the switch mode power supply to operate at the minimum voltage necessary to operate a power load and charge batteries. Furthermore, the switch mode power supply is capable of producing the maximum power required by the system, such as when the battery charger is used in conjunction with operation of a electronic device with peak load demands such as when a hard disk is accessed in a portable computer. Two control mechanisms are found in the battery charging system. The first mechanism is an input used to control the switch mode power supply output voltage from an external source. In one embodiment, this is done by referencing a first voltage to that internal to the switch mode power supply. The second mechanism is to limit the current within the switch mode power supply not controlled by an external source. This current limiting feature is linear and is set at an absolute limit point. Each limiter supplies charge current to a battery, which charge current is monitored and compared to a reference voltage with the resulting error voltage used to control the output of a series pass controller, such as a transistor.