Patent ID: 7164237

Claim:
Circuit arrangement for operating a lamp load comprising input terminals for connection to a supply voltage source, a series arrangement I comprising a first switching element and a second switching element and connecting the input terminals, a control circuit coupled to respective control electrodes of the first switching element and the second switching element for controlling the conductive state of the first and the second switching element, a series arrangement II comprising a first circuit element A and a second circuit element B and connecting the input terminals, a first load circuit comprising a first ballast inductor and first lamp connection terminals and connecting a terminal N 1 of the series arrangement I between the switching elements to a terminal of the series arrangement II between the first circuit element A and the second circuit element B, characterized in that the circuit arrangement comprises a series arrangement III comprising terminal N 1 , a first diode D 1 and a second diode D 2 and connecting the first switching element and the second switching element, terminal N 1 being situated between first diode D 1 and second diode D 2 , a series arrangement IV comprising a third diode D 3 and a fourth diode D 4 and connecting the first switching element and the second switching element, a fifth diode D 5 shunting the first switching element and diode D 1 , a sixth diode D 6 shunting the first switching element and diode D 3 , a seventh diode D 7 shunting the second switching element and diode D 2 , an eighth diode D 8 shunting the second switching element and diode D 4 , a second load circuit comprising a second ballast inductor and second lamp connection terminals and connecting a terminal N 2 of the series arrangement IV, situated between the third diode D 3 and the fourth diode D 4 to a terminal of the series arrangement II between the first circuit element A and the second circuit element B.