METHODS AND APPARATUS FOR COMMUNICATING CURRENT LEVELS WITHIN A LIGHTING APPARATUS INCORPORATING A VOLTAGE CONVERTER
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Abstract
Circuits for sensing current levels within an apparatus are disclosed. In specific cases, a constant voltage power supply is used to power an LED lighting apparatus in which there are uncertainties within the forward voltages of the LEDs, which in turn creates uncertainty with respect to the current level flowing through the LEDs. To manage these uncertainties, the current flowing through the LEDs is measured by determining a voltage level across a known resistor and calculating the current level. To prevent the known resistor from causing a significant reduction in the efficiency of the overall light engine, the circuit includes one or more transistors in parallel with the known resistor to reduce the effective resistance in the LED circuit during times that the current is not being sensed.
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Citations
43 Claims
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1-23. -23. (canceled)
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24. A lighting apparatus comprising:
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a voltage converter operable to receive an input voltage and generate an output voltage defined between a high voltage rail and a low voltage rail; at least one Light Emitting Diode (LED) and a switching element coupled in series between the high voltage rail and the low voltage rail; a controller operable to control the switching element to cause the LED to generate a light output that comprises a modulated signal that includes information related to the lighting apparatus. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A control apparatus comprising:
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a voltage converter operable to receive an input voltage and generate an output voltage defined between a high voltage rail and a low voltage rail;
the voltage converter being adapted to be coupled to at least one Light Emitting Diode (LED) and a switching element coupled in series between the high voltage rail and the low voltage rail; anda controller operable to control the switching element to cause the LED to generate a light output that comprises a modulated signal that includes information related to the lighting apparatus. - View Dependent Claims (38, 39, 40, 41, 42)
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43. A method comprising:
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generating an output voltage defined between a high voltage rail and a low voltage rail, at least one Light Emitting Diode (LED) and a switching element coupled in series between the high and low voltage rails; determining a current level flowing from the high voltage rail to the low voltage rail; and controlling the switching element to cause the LED to generate a light output that comprises a modulated signal that includes an indication of the current flowing from the high voltage rail to the low voltage rail.
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Specification