LED lighting system comprising: - a power supply circuit for supplying a LED current comprising - input terminals (K1, K2) for connection to a supply voltage source and output terminals (K3, K4), - modulation circuitry (MS, DC2), coupled between the output terminals, for alternately maintaining the voltage between the output terminals at a high level during a first time interval and a low level during a second time interval, - a current sensor (R1, R2, S1) for sensing the current through the output terminals during the second time interval, - a driver circuit (DC1, DC2), coupled between the input terminals and the output terminals and coupled to the current sensor, for generating the LED current out of a supply voltage supplied by the supply voltage source, wherein the LED current equals the current sensed by the current sensor multiplied by a predetermined constant multiplication factor and for supplying the LED current to the output terminals during each first time interval, wherein the LED lighting system further comprises a low voltage source coupled between the output terminals of the power supply circuit - a LED module comprising: - LED module input terminals (K5, K6) for connection to the output terminals of the power supply circuit, - a LED load coupled between the LED module input terminals, wherein the LED module further comprises a current source coupled between the LED module input terminals for, during each second time interval,generating a sensor current through the current sensor that is equal to a desired LED current divided by the predetermined constant multiplication factor, and wherein the low level voltage that is present between the output terminals of the power supply circuit during each second time interval is lower than a forward voltage of the LED load. - a power supply circuit for supplying a LED current comprising - input terminals (K1, K2) for connection to a supply voltage source and output terminals (K3, K4), - modulation circuitry (MS, DC2), coupled between the output terminals, for alternately maintaining the voltage between the output terminals at a high level during a first time interval and a low level during a second time interval, - a current sensor (R1, R2, S1) for sensing the current through the output terminals during the second time interval, - a driver circuit (DC1, DC2), coupled between the input terminals and the output terminals and coupled to the current sensor, for generating the LED current out of a supply voltage supplied by the supply voltage source, wherein the LED current equals the current sensed by the current sensor multiplied by a predetermined constant multiplication factor and for supplying the LED current to the output terminals during each first time interval, wherein the LED lighting system further comprises a low voltage source coupled between the output terminals of the power supply circuit - input terminals (K1, K2) for connection to a supply voltage source and output terminals (K3, K4), - modulation circuitry (MS, DC2), coupled between the output terminals, for alternately maintaining the voltage between the output terminals at a high level during a first time interval and a low level during a second time interval, - a current sensor (R1, R2, S1) for sensing the current through the output terminals during the second time interval, - a driver circuit (DC1, DC2), coupled between the input terminals and the output terminals and coupled to the current sensor, for generating the LED current out of a supply voltage supplied by the supply voltage source, wherein the LED current equals the current sensed by the current sensor multiplied by a predetermined constant multiplication factor and for supplying the LED current to the output terminals during each first time interval, wherein the LED lighting system further comprises a low voltage source coupled between the output terminals of the power supply circuit - a LED module comprising: - LED module input terminals (K5, K6) for connection to the output terminals of the power supply circuit, - a LED load coupled between the LED module input terminals, wherein the LED module further comprises a current source coupled between the LED module input terminals for, during each second time interval,generating a sensor current through the current sensor that is equal to a desired LED current divided by the predetermined constant multiplication factor, and wherein the low level voltage that is present between the output terminals of the power supply circuit during each second time interval is lower than a forward voltage of the LED load. - LED module input terminals (K5, K6) for connection to the output terminals of the power supply circuit, - a LED load coupled between the LED module input terminals,