Patent ID: 8531122
Filing Date: 2013-09-10
Classification: H05B

Abstract:
1. A circuit arrangement for operating a discharge lamp, the circuit arrangement comprising: an input having a first input terminal and a second input terminal for connecting a supply voltage; a first electronic switch which has a control electrode, a working electrode and a reference electrode, wherein the working electrode is coupled to the first input terminal; a first diode whose anode is coupled to the second input terminal and whose cathode is coupled to the reference electrode of the first electronic switch while forming a first junction point; a control device which is coupled to the control electrode of the first electronic switch for the purpose of driving the first electronic switch; an output having a first output terminal and a second output terminal for providing an output voltage to the discharge lamp; an inductor which is arranged in series with one of the output terminals; a lamp inductor which is coupled between the first junction point and the first output terminal; and a first capacitor which is coupled between the first output terminal and the anode of the first diode; wherein the control device is embodied to switch the first electronic switch continuously to conducting for an on-time and to non-conducting for an off-time; wherein the circuit arrangement further comprises a voltage-measuring device embodied to measure the output voltage, wherein the voltage-measuring device is embodied to provide at its output a signal which is correlated with the measured output voltage, wherein the voltage-measuring device is coupled to the control device for the purpose of transmitting said signal to the control device, and wherein the control device is embodied to vary the off-time as a function of the measured output voltage, wherein the control device is embodied to vary the off-time in such a way that the following applies: where T