LAMP DRIVER FOR OPERATING A GAS DISCHARGE LAMP

摘要

In order to determine a current supplied by a SMPS power supply circuit and to determine a current flowing through a lamp coupled to the SMPS power supply circuit, a lamp driver circuit for operating a gas discharge lamp is proposed, which comprises a switched mode power supply, SMPS, circuit and a first and a second output terminal for supplying a lamp current to the gas discharge lamp. The lamp driver circuit further comprises an output capacitor connected between the SMPS circuit and a ground terminal and comprises a resistive shunt connected between the ground terminal and the second output terminal for determining the lamp current. An output current sensing circuit for determining a SMPS output current is comprised in the lamp driver circuit instead of a further resistive shunt, which would require a differential voltage measurement. The output current sensing circuit comprises a sensing resistor connected in series with a sensing capacitor, the series connection being connected in parallel to the output capacitor.