Patent ID: 6535401
Filing Date: 2003-03-18
Classification: H05B

Abstract:
A circuit arrangement for energizing a lamp comprising:input terminals which are to be connected to a DC voltage source, an inverter coupled to the input terminals for generating a lamp current from the DC voltage supplied by the DC voltage source, which inverter comprises a switching element coupled to the input terminals, a control circuit coupled to a control electrode of the switching element, which control circuit serves to generate a control signal for rendering the switching element alternately conducting and non-conducting, a pulse duration modulator, which is coupled to the control circuit and which is used to set the duty cycle of the control signal, said duty cycle being directly proportional to a digital signal present at an output of the pulse duration modulator, characterized in that said pulse duration modulator is further provided with a circuit part M for periodically modulating the digital signal, each period of this modulation comprising a first time interval wherein the digital signal has a first value, and a second time interval wherein the digital signal has a second value, said first and said second value being independently adjustable by the circuit part M.