3-WAY, PHASE-CUT DIMMABLE LED DRIVER
First Claim
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1. An LED driver, comprising:
- a rectifier circuit with an AC input having first, second, and third AC input terminalsa pulse width modulated power circuit providing a DC output to drive at least one LED light source, the power circuit comprising;
a first switching device comprising a control input terminal and operative according to a pulse width modulated control input signal to control application of power to the at least one LED light source,a pulse width modulation controller, including an amplifier input, a gain input, and a pulse width modulator with a drive output providing the pulse width modulated control signal to the control input terminal of the switching device to set a level of output power provided to the at least one LED light source at least partially according to the amplifier input and the gain input;
a sensing circuit coupled with the first and third AC input terminals and providing a sensor signal to the gain input of the pulse width modulation controller, the sensing circuit providing the sensor signal at a first level if an input voltage is applied to the third AC input terminal and providing the sensor signal at a lower second level if no input voltage is applied to the third AC input terminal;
a first attenuator circuit comprising a first attenuator input coupled with the second AC input terminal and a first attenuator output coupled with the gain input of the pulse width modulation controller, the first attenuator circuit operative to selectively reduce a voltage of the gain input if an input voltage is applied to the second AC input terminal to decrease the power provided to the at least one LED light source; and
a second attenuator circuit comprising a second attenuator input coupled with the third AC input terminal and a second attenuator output coupled with the amplifier input of the pulse width modulation controller, the second attenuator circuit operative to selectively reduce a voltage of the amplifier input if an input voltage is applied to the third AC input terminal to increase the power provided to the at least one LED light source.
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Abstract
An LED driver is presented with a sensing circuit and attenuator circuits to provide three-way switched dimming as well as phase-cut dimming to control the output power driving an LED load.
26 Citations
21 Claims
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1. An LED driver, comprising:
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a rectifier circuit with an AC input having first, second, and third AC input terminals a pulse width modulated power circuit providing a DC output to drive at least one LED light source, the power circuit comprising; a first switching device comprising a control input terminal and operative according to a pulse width modulated control input signal to control application of power to the at least one LED light source, a pulse width modulation controller, including an amplifier input, a gain input, and a pulse width modulator with a drive output providing the pulse width modulated control signal to the control input terminal of the switching device to set a level of output power provided to the at least one LED light source at least partially according to the amplifier input and the gain input; a sensing circuit coupled with the first and third AC input terminals and providing a sensor signal to the gain input of the pulse width modulation controller, the sensing circuit providing the sensor signal at a first level if an input voltage is applied to the third AC input terminal and providing the sensor signal at a lower second level if no input voltage is applied to the third AC input terminal; a first attenuator circuit comprising a first attenuator input coupled with the second AC input terminal and a first attenuator output coupled with the gain input of the pulse width modulation controller, the first attenuator circuit operative to selectively reduce a voltage of the gain input if an input voltage is applied to the second AC input terminal to decrease the power provided to the at least one LED light source; and a second attenuator circuit comprising a second attenuator input coupled with the third AC input terminal and a second attenuator output coupled with the amplifier input of the pulse width modulation controller, the second attenuator circuit operative to selectively reduce a voltage of the amplifier input if an input voltage is applied to the third AC input terminal to increase the power provided to the at least one LED light source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification