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:
Jul. 23, 2013
Filed:
Jan. 21, 2010
Bin Zhao, Irvine, CA (US);
Bin Zhao, Irvine, CA (US);
Freescale Semiconductor, Inc., Austin, TX (US);
Abstract
A light emitting diode (LED) system implements a power management technique. The LED system includes a plurality of LED drivers connected in series, each LED driver configured to regulate the current flowing through a corresponding subset of a plurality of LED strings. Each LED driver determines the tail voltages of the one or more LED strings of the corresponding subset. Each LED driver, except for the first LED driver in the series, also receives a voltage representative of the minimum tail voltage of the other subsets regulated by the upstream LED drivers. Each LED driver then provides the lowest of the voltage received from the upstream LED driver and the one or more tail voltages of the corresponding subset to the downstream LED driver. In this manner a voltage representative of the minimum tail voltage of the plurality of LED strings is cascaded through the series. A feedback controller monitors the minimum tail voltage represented by this cascaded voltage and accordingly adjusts an output voltage provided to the head ends of the plurality of LED strings.