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.