CIRCUIT ARRANGEMENT FOR CONTROLLING A LED UNIT AND METHOD OF OPERATING THE SAME

摘要

A circuit arrangement (3, 3') for controlling the brightness of at least one LED unit (2) is provided, comprising an input (8) for receiving a phase-cut operating voltage from a power supply (4), a signal processor (14, 14'), connected with said input (8) and adapted to provide a dimming signal (12) for said at least one LED unit (2) from said operating voltage. To allow an efficient reduction of noise in the dimming signal (12) but simultaneously to allow an improved dimming of said LED unit (2), said signal processor (14, 14') is being configured to operate at least in a noise suppression mode (30) and a dimming mode (31). A control device (15, 15') is provided, connected with said signal processor (14, 14') and configured to set the mode of said signal processor (14, 14') in dependence of the variation in said operating voltage.