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Secondary Side Post Regulation for LED Backlighting

  • US 20070159421A1
  • Filed: 01/09/2007
  • Published: 07/12/2007
  • Est. Priority Date: 01/10/2006
  • Status: Active Grant
First Claim
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1. A powering arrangement for a plurality of light emitting diode (LED) strings, said powering arrangement comprising:

  • a transformer exhibiting a primary winding and a plurality of secondary windings coupled to said primary winding;

    a first plurality of electronically controlled switches, each of said first plurality of electronically controlled switches associated with a particular one of said plurality of secondary windings;

    a plurality of LED strings, each of said plurality of LED strings associated with, and arranged to receive power from, a particular one of said plurality of secondary windings responsive to the respective first electronically controlled switch;

    a second plurality of electronically controlled switches, each of said second plurality of electronically controlled switches arranged in series with a particular one of said plurality of LED strings and operable to pulseably enable the flow of current through said particular LED string;

    a plurality of synchronized samplers, each of said plurality of synchronized samplers in communication with a particular one of said plurality of LED strings and arranged to sample said pulseably enabled current flow and output a sampled representation; and

    a plurality of feedback circuits each associated with a particular one of said plurality of synchronized samplers, each of said plurality of feedback circuits operable to control a respective one of said first electronically controlled switches responsive to said respective sampled representation.

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