SYSTEM FOR DRIVING A LAMP

摘要

A driver (10) for driving a LED (2) comprises: an ACDC converter (5) receiving AC mains voltage and generating DC output current; a chopper (6) receiving the DC output current and provide a regularly interrupted output current; a clock generator (20) generating a clock signal (SCL); a controller (50) receiving a user input signal (Su) indicating a dimming level, receiving the clock signal, receiving a mains signal (SM) representing the actual phase of the mains voltage, and generating a control signal (Sc) for the chopper. The chopper is responsive to the controller's control signal as regards the switching moments of the output current. The controller calculates the required duty cycle on the basis of the user input signal. The controller synchronizes its control signal with the mains signal. The controller sets an arbitrary value for the phase difference of the output control signal with respect to the input mains signal.