CONTROL UNIT FOR A LED ASSEMBLY AND LIGHTING SYSTEM

摘要

A lighting system comprising an LED assembly that comprises a first and second LED unit said LED units being serial connected is described. The system comprises; - a switched mode power supply for powering the LED assembly; - a control unit for controlling the LED assembly the control unit being arranged to: ?receive an input signal representing a desired output characteristic of the LED assembly, ?determine a first and second duty cycle for the respective first and second LED units associated with a nominal current of the switched mode power supply, for providing the desired output characteristic, ?determine the largest of the first and second duty cycles for respective LED units, ?determine a reduced current based on at least the largest of the duty cycles, ?adjust the first and second duty cycle for respective LED units based on the reduced current or the largest of the duty cycles, ?provide output data for the LED assembly and the switched mode power supply based on the adjusted first and second duty cycles and the reduced current. The LED assembly of the system further comprises a capacitor connectable in parallel to the first and second LED units by operating a switch connected in series with the capacitor and wherein the control unit is arranged to control the switch based on at least one of the reduced current and the input signal.