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Light emitting device control circuit with dimming function and control method thereof

  • US 9,247,601 B2
  • Filed: 12/04/2014
  • Issued: 01/26/2016
  • Est. Priority Date: 12/16/2013
  • Status: Expired due to Fees
First Claim
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1. A light emitting device control circuit with dimming function, comprising:

  • a dimmer circuit configured to operably generate an AC dimming voltage according to an AC voltage;

    a rectifier and filter circuit, which is coupled to the dimmer circuit, and configured to operably generate an input voltage according to the AC dimming voltage;

    a power converter circuit, which is coupled to the rectifier and filter circuit, and configured to operably operate at least one power switch therein according to a control signal to convert the input voltage to an output voltage, wherein the output voltage is supplied to a light emitting device circuit; and

    a headroom voltage regulation circuit, which is coupled to the power converter circuit, and configured to operably generate the control signal according to a reference value and a difference between the input voltage and the output voltage, and regulate the difference at a level corresponding to the reference value by a feedback control loop;

    wherein the headroom voltage regulation circuit includes;

    a difference sampling circuit, configured to operably generate a headroom voltage according to the difference; and

    a comparison circuit, which is coupled to the difference sampling circuit, and configured to operably generate the control signal according to the headroom voltage and a reference voltage, wherein the reference voltage corresponds to the reference value.

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