A lighting circuit structured to turn on a plurality of semiconductor light sources, comprising: a plurality of current sources (210_1; 210_N) each of which is to be coupled to a corresponding semiconductor light source (102_1; 102_N) in series; a switching converter structured to supply a driving voltage (V OUT) across each of a plurality of series connection circuits each formed of the semiconductor light source (102_i) and the current source (210_i), with i being 1 through N; and a converter controller employing a ripple control method, wherein the converter controller comprises: a plurality of comparators (252_i) respectively assigned to the plurality of current sources (210_i), and each structured to compare a voltage (V LEDi) across a corresponding current source (210_i) with a predetermined bottom limit voltage (V BOTTOM); and a logic gate structured to receive outputs of the plurality of comparators (252_i) and to perform a logical operation on the outputs of the plurality of comparators (252_i), wherein an assertion of an output of the logic gate indicates a voltage (V LEDi) across at least one of the plurality of current sources (210_1; 210_N) decreasing to the bottom limit voltage (V BOTTOM), characterized in that the converter controller is structured to turn on a switching transistor (M 1) of the switching converter in response to the assertion of the output of the logic gate performing the logical operation on the outputs of the plurality of comparators (252_i), wherein the assertion of the output of the logic gate indicates a voltage (V LEDi) across at least one of the plurality of current sources (210_1; 210_N) decreasing to a bottom limit voltage (V BOTTOM) and wherein the output of the logic gate is a binary digital signal and the output of the logic gate is used as a trigger input for turn-on of the switching transistor. a plurality of current sources (210_1; 210_N) each of which is to be coupled to a corresponding semiconductor light source (102_1; 102_N) in series; a switching converter structured to supply a driving voltage (V OUT) across each of a plurality of series connection circuits each formed of the semiconductor light source (102_i) and the current source (210_i), with i being 1 through N; and a converter controller employing a ripple control method, wherein the converter controller comprises: a plurality of comparators (252_i) respectively assigned to the plurality of current sources (210_i), and each structured to compare a voltage (V LEDi) across a corresponding current source (210_i) with a predetermined bottom limit voltage (V BOTTOM); and a logic gate structured to receive outputs of the plurality of comparators (252_i) and to perform a logical operation on the outputs of the plurality of comparators (252_i), wherein an assertion of an output of the logic gate indicates a voltage (V LEDi) across at least one of the plurality of current sources (210_1; 210_N) decreasing to the bottom limit voltage (V BOTTOM), characterized in that the converter controller is structured to turn on a switching transistor (M 1) of the switching converter in response to the assertion of the output of the logic gate performing the logical operation on the outputs of the plurality of comparators (252_i), wherein the assertion of the output of the logic gate indicates a voltage (V LEDi) across at least one of the plurality of current sources (210_1; 210_N) decreasing to a bottom limit voltage (V BOTTOM) and wherein the output of the logic gate is a binary digital signal and the output of the logic gate is used as a trigger input for turn-on of the switching transistor. a plurality of comparators (252_i) respectively assigned to the plurality of current sources (210_i), and each structured to compare a voltage (V LEDi) across a corresponding current source (210_i) with a predetermined bottom limit voltage (V BOTTOM); and a logic gate structured to receive outputs of the plurality of comparators (252_i) and to perform a logical operation on the outputs of the plurality of comparators (252_i), wherein an assertion of an output of the logic gate indicates a voltage (V LEDi) across at least one of the plurality of current sources (210_1; 210_N) decreasing to the bottom limit voltage (V BOTTOM), characterized in that the converter controller is structured to turn on a switching transistor (M 1) of the switching converter in response to the assertion of the output of the logic gate performing the logical operation on the outputs of the plurality of comparators (252_i), wherein the assertion of the output of the logic gate indicates a voltage (V LEDi) across at least one of the plurality of current sources (210_1; 210_N) decreasing to a bottom limit voltage (V BOTTOM) and wherein the output of the logic gate is a binary digital signal and the output of the logic gate is used as a trigger input for turn-on of the switching transistor.