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LED DIMMER CIRCUIT

  • US 20120249000A1
  • Filed: 03/28/2012
  • Published: 10/04/2012
  • Est. Priority Date: 03/29/2011
  • Status: Active Grant
First Claim
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1. A light emitting diode (LED) dimmer circuit for performing LED dimming, comprising:

  • a triode for alternating current (TRIAC) dimmer for gating an alternating current (AC) waveform from an AC power source at a proportion according to a control signal and outputting a TRIAC pulse having part of the AC waveform missing;

    a rectifying circuit for rectifying the TRIAC pulse from the TRIAC dimmer;

    a current sensing circuit for detecting a drive current value flowing to an LED driven by an output of the rectifying circuit;

    a control transistor for switching said drive current on and off;

    a comparator circuit for comparing said drive current value detected by the current sensing circuit and a predetermined value;

    a control circuit for turning off said control transistor when said drive current value exceeds said predetermined value in accordance with a comparison result of the comparator circuit and turning on said control transistor when a trigger pulse is applied;

    a converter circuit for converting said TRIAC pulse to a DC voltage signal; and

    a change circuit for changing said drive current value or said predetermined value to be input to said comparator circuit in accordance with said DC voltage signal.

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