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LED (light-emitting diode) string derived controller power supply

  • US 9,713,206 B2
  • Filed: 07/16/2015
  • Issued: 07/18/2017
  • Est. Priority Date: 03/20/2014
  • Status: Active Grant
First Claim
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1. A lighting circuit, comprising:

  • a plurality of sets of series-connected light-emitting diodes (LEDs), wherein a first LED set of one or more of the LEDs includes a first terminal coupled between an input voltage source terminal and an auxiliary power supply terminal and a second LED set of one or more of the LEDs includes a current input terminal and a ground terminal;

    a switching power converter having a magnetic energy-storing element and a switching element for controlling a current supplied through the plurality of series connected light-emitting diodes;

    a control circuit for controlling the switching element of the switching power converter, wherein;

    the control circuit includes a power supply input terminal coupled to the auxiliary power supply terminal of the first LED set;

    a switching circuit, wherein the switching circuit includes;

    a first switch coupled to the auxiliary power supply terminal of the first LED set and the ground terminal of the second LED set;

    a second switch coupled between the auxiliary power supply terminal of the first LED set and the current input terminal of the second LED set;

    a string controller circuit coupled to control terminals of the first and second switches, wherein the string controller circuit is configured to;

    generate a first control signal to control the first switch to alternately allow current to flow from the auxiliary power supply terminal to the control circuit and shunt the auxiliary power supply terminal to the ground terminal; and

    generate a second control signal to control the second switch to intermittently couple the auxiliary power supply terminal to the current input terminal of the second LED set.

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