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TWO-WIRE DIMMER SWITCH FOR LOW-POWER LOADS

  • US 20120033471A1
  • Filed: 09/14/2011
  • Published: 02/09/2012
  • Est. Priority Date: 11/25/2009
  • Status: Active Grant
First Claim
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1. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:

  • a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the thyristor having a gate for conducting a gate current to render the thyristor conductive;

    a gate coupling circuit coupled between the first main load terminal and the gate of the thyristor, the gate coupling circuit comprising a control input for receiving a drive voltage, the gate coupling circuit operable to conduct the gate current through the gate of the thyristor in response to the drive voltage; and

    a control circuit coupled to at least one of the main load terminals of the thyristor, the control circuit further coupled to the control input of the gate coupling circuit and operable to generate the drive voltage, the control circuit controls the drive voltage to cause the gate coupling circuit to conduct the gate current to thus render the thyristor conductive a t a firing time during a half cycle of the AC power source, the control circuit controls the drive voltage to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle;

    wherein the gate coupling circuit conducts approximately no net average current through the control input in order to remain conductive and to thus be able to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle.

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