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. 20, 2013
Filed:
Nov. 17, 2011
Matthew Weng, San Ramon, CA (US);
Matthew Weng, San Ramon, CA (US);
Micrel, Inc., San Jose, CA (US);
Abstract
A step-down hysteretic current LED driver circuit implements frequency regulation to adjust the hysteresis levels of a hysteretic comparator in the control circuit of the LED driver to keep the switching frequency of the inductor current constant. More specifically, the switching frequency of the inductor current is kept constant by increasing or decreasing the hysteresis window of the hysteretic comparator. In this manner, the switching frequency of the LED driver is kept constant or predictable. In one embodiment, the control circuit of the LED driver includes a frequency regulator to monitor the switching frequency and adjusts the hysteresis window accordingly to maintain a constant switching frequency.