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. 10, 2012
Filed:
Aug. 26, 2008
Dale R. Eagar, Black Forest, CO (US);
Joseph V. Denicholas, Longmont, CO (US);
Dale R. Eagar, Black Forest, CO (US);
Joseph V. DeNicholas, Longmont, CO (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A system includes a first transistor configured to control a current through one or more LEDs and an inductor coupled in series with the one or more LEDs. The system also includes a current mode switcher configured to control the first transistor so that the inductor has a substantially constant ripple current. The system may further include a resistor and a second transistor coupled across the one or more LEDs and an integrating capacitor coupled in series with the second transistor. The switcher may include a driver configured to drive the first transistor to turn the first transistor on and off. The switcher may also include a detector configured to turn off the first transistor when a current through the first transistor exceeds a first threshold. The switcher may further include a timer configured to turn on the first transistor when a voltage on the integrating capacitor exceeds a second threshold.