Intensity control of LEDs interfacing three-way sockets
A light-emitting diode (LED) lighting fixture is configured to interface a three-way socket and provide at least two levels of output light intensity. A detection unit determines whether one or both input voltages lines of the three-way socket are active and provides a control signal to an LED controller indicating which input voltage lines are active. The LED controller is configured to provide different output current levels to an LED bank based on whether one or both input voltage lines are active. By adjusting the output current level based on which input lines are active, the LED lighting fixture provides at least two output lighting intensity levels. LED lighting fixtures according to various embodiments can therefore serve as a direct replacement for three-way incandescent bulbs.
1. A light-emitting diode (LED) lighting fixture configured to receive signals from a first input voltage line and a second input voltage line, the LED lighting fixture comprising:
an LED bank including one or more LEDs; and
an LED controller configured to detect whether the first and second input voltage lines are active and to provide regulated current to the LED bank, the LED controller configured to:
provide regulated output current at a first level to a first portion of the LED bank responsive to detecting the first input voltage line is active and the second input voltage line is not active; and
provide a regulated output current at a second level to a second portion of the LED bank responsive to detecting the first and second input voltage lines are active, the second portion of the LED bank at least partially overlapping the first portion.
2. The LED lighting fixture of claim 1 , further comprising:
a detection circuit configured to detect whether the first and second input voltage lines are active and generate first and second detection signals, the first detection signal indicative of the first input voltage and the second detection signal indicative of the second input voltage; and
a decoding circuit configured to receive the first and second detection signals and generate a control signal based on the first and second detection signals, wherein the LED controller is configured to detect whether the first and second input voltage lines are active based on the control signal.
3. The LED lighting fixture of claim 2 , wherein the control signal has a first value responsive to the first detection signal indicating that the first input voltage line is active and the second input voltage line is not active and has a second value responsive to the first and second detection signals indicating that the first and second input voltage lines are active.
4. The LED lighting fixture of claim 1 , wherein the second current level is greater than the first current level.
5. A method for controlling output light intensity of a light-emitting diode (LED) lighting fixture configured to receive signals from a first input voltage line and a second input voltage line, the method comprising:
detecting whether the first and second input voltage lines are active;
providing regulated output current at a first level to a first portion of the LED bank responsive to detecting the first input voltage line is active and the second input voltage line is not active; and
providing a regulated output current at a second level to a second portion of the LED bank responsive to detecting the first and second input voltage lines are active, the second portion of the LED bank at least partially overlapping the first portion.
6. The method of claim 5 , further comprising:
generating a first and a second detection signal, the first detection signal indicative of the first input voltage and the second detection signal indicative of the second input voltage; and
generating a control signal based on the first and second detection signals, wherein detecting whether the first and second input voltage lines are active comprises detecting whether the first and second input voltage lines are active based on the control signal.
7. The method of claim 6 , wherein the control signal has a first value responsive to the first detection signal indicating that the first input voltage line is active and the second input voltage line is not active and has a second value responsive to the first and second detection signals indicating that the first and second input voltage lines are active.
8. The method of claim 5 , wherein the second current level is greater than the first current level.