| 摘要 |
As apparatus for controlling operating parameters for a light emitting diode (LED). A driver receives an input voltage from a voltage source and a control signal. The driver provides a driver output current to the LED based on the control signal. The LED has an LED voltage as a function of the driver output current and has an LED power as a function of said LED voltage and said driver output current. A controller determines the LED voltage and produces the control signal provided to the driver as a function of the LED voltage. The control signal corresponds to a constant driver output current when the LED voltage is less than a predetermined voltage value. The control signal corresponds to a varying driver output current for substantially maintaining the LED power at a constant predetermined power value web the LED voltage is greater than the predetermined voltage value.
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