Patent ID: 7944420
Filing Date: 2011-05-17
Classification: G09G,H05B

Abstract:
1. An apparatus used with a voltage source for energizing a light emitting diode (LED), said apparatus comprising: a driver receiving an input voltage from the voltage source and a control signal and providing a driver output current to the LED based on the control signal, said driver having a boost buck topology, said LED having an LED voltage as a function of said driver output current and having an LED power as a function of said LED voltage and said driver output current; and a controller determining the LED voltage and producing the control signal provided to the driver as a function of the LED voltage, said control signal corresponding to a constant driver output current when the LED voltage is less than a predetermined voltage value, said control signal corresponding to a varying driver output current for substantially maintaining the LED power at a constant predetermined power value when the LED voltage is greater than the predetermined voltage value.