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:
Nov. 24, 2009
Filed:
Oct. 01, 2007
Thruston Awalt, Los Gatos, CA (US);
Hardik Dineshchandra Patel, Milpitas, CA (US);
Thruston Awalt, Los Gatos, CA (US);
Hardik Dineshchandra Patel, Milpitas, CA (US);
Micrel, Incorporated, San Jose, CA (US);
Abstract
A LED driver circuit avoids undesirable light generated by a LED due to leakage current by shunting the output terminal to the feedback terminal during periods when it is desired that the LED remain turned off. The shunting operation is achieved by providing a switch (e.g., a FET) that is connected between the output and feedback terminals of the LED, and is controlled by the user supplied reference signal. During active operation (i.e., when the user supplied reference signal is 'enabled' and the LED is lit), the switch remains open, allowing the driver circuit to generate the desired driving voltage across the LED. During inactive periods (i.e., when the user supplied reference signal is 'disabled' and the LED is intended to be off), the switch is closed, which couples the output and feedback terminals to generate an essentially zero voltage drop across the LED.