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:
Mar. 27, 2012
Filed:
Jun. 04, 2007
Alberto Ferro, Preganziol, IT;
Alberto Ferro, Preganziol, IT;
Osram AG, Munich, DE;
Abstract
A LED driver arrangement including a switching-mode stage to produce a drive current for feeding a LED from a DC input; a current sensor for the current fed to the LED for producing a feedback signal; error amplifier circuitry for generating a control signal from the feedback signal; and control circuitry sensitive to the control signal to control the switching-mode stage so that the drive current fed by the switching-mode stage to the LED corresponds to the LED current. An opto-coupler feeds the control signal to the control circuitry, and the opto-coupler having associated biasing circuitry to increase current on the opto-coupler when the LED current decreases. The opto-coupler is configured to saturate when the drive current reaches a minimum level. There is also an auxiliary supply voltage for the control circuitry to keep the auxiliary supply voltage above a minimum level when the opto-coupler is saturated.