A power supply system for a load unit , the load unit including a first terminal, a second terminal, and a plurality of loads that are coupled in series between the first and second terminals thereof, said power supply system being characterized by : a current driver circuit to receive a pulse signal (GATE), and generating an output current (I L ) based on the pulse signal (GATE); the output current (I L ) increasing within each pulse of the pulse signal (GATE), and decreasing outside each pulse of the pulse signal (GATE); a sensor circuit coupled to said current driver circuit , and connectable to the first terminal of the load unit ; said sensor circuit when connected to the first terminal of the load unit allowing the output current (I L ) to flow therethrough from said current driver circuit to the first terminal of the load unit , and sensing the output current (I L ) to generate a sensed voltage (V Sense ) ; a control circuit connectable to the loads , and when connected to the loads , adapted to receive a control input; for each of the loads , said control circuit being operable, based on the control input, to allow or not to allow the output current (I L ) to flow through the load ; a voltage generator circuit to receive the control input, and generating a reference voltage (V REF_COM ) based on the control input; the reference voltage (V REF_COM ) being correlated to a number of one(s) of the loads through which the output current (I L ) flows; and a signal generator circuit coupled to said sensor circuit , said voltage generator circuit and said current driver circuit , and to receive the sensed voltage (V Sense ) and the reference voltage (V REF_COM ) respectively from said sensor circuit and said voltage generator circuit ; said signal generator circuit generating a first threshold voltage (V HB ) and a second threshold voltage (V LB ) based on the reference voltage (V REF_COM ) , and comparing the sensed voltage (V Sense ) with the first and second threshold voltages (V HB , V LB ) to generate the pulse signal (GATE) for receipt by said current driver circuit . a current driver circuit to receive a pulse signal (GATE), and generating an output current (I L ) based on the pulse signal (GATE); the output current (I L ) increasing within each pulse of the pulse signal (GATE), and decreasing outside each pulse of the pulse signal (GATE); a sensor circuit coupled to said current driver circuit , and connectable to the first terminal of the load unit ; said sensor circuit when connected to the first terminal of the load unit allowing the output current (I L ) to flow therethrough from said current driver circuit to the first terminal of the load unit , and sensing the output current (I L ) to generate a sensed voltage (V Sense ) ; a control circuit connectable to the loads , and when connected to the loads , adapted to receive a control input; for each of the loads , said control circuit being operable, based on the control input, to allow or not to allow the output current (I L ) to flow through the load ; a voltage generator circuit to receive the control input, and generating a reference voltage (V REF_COM ) based on the control input; the reference voltage (V REF_COM ) being correlated to a number of one(s) of the loads through which the output current (I L ) flows; and a signal generator circuit coupled to said sensor circuit , said voltage generator circuit and said current driver circuit , and to receive the sensed voltage (V Sense ) and the reference voltage (V REF_COM ) respectively from said sensor circuit and said voltage generator circuit ; said signal generator circuit generating a first threshold voltage (V HB ) and a second threshold voltage (V LB ) based on the reference voltage (V REF_COM ) , and comparing the sensed voltage (V Sense ) with the first and second threshold voltages (V HB , V LB ) to generate the pulse signal (GATE) for receipt by said current driver circuit . <EOS>