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:
Aug. 04, 2009
Filed:
Aug. 04, 2005
Luan VU, San Jose, CA (US);
Luan Vu, San Jose, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A voltage regulation and battery charging system is provided. The system can simultaneously provide a regulated output voltage and charge a battery. The system includes a battery charger circuit, a voltage regulator circuit, and a voltage tracking circuit. A voltage divider is used to provide the voltage regulator circuit with a feedback voltage from the output voltage. Further, the voltage tracking circuit is operable to draw current from the voltage divider such that the regulated output voltage tracks the battery voltage if the battery voltage is above a threshold voltage. The voltage tracking circuit includes an op amp, a current mirror, and a resistor that is coupled between the inverting input of the op amp and the battery. The noninverting input of the op amp receives the threshold voltage. Additionally, the output of the op amp is coupled to the gates of the transistors in the current mirror.