A driver arrangement for LED light sources includes a transformer having primary and secondary winding connections. A first electronic switch (SW1) controls current flow through the primary winding, and a sensing resistor is coupled to the primary winding to produce a current sensing signal. A second electronic switch (SW2) is sensitive to the sensing signal to switch off SW1 as current flow through the primary winding reaches a given threshold. SW1 is thus alternatively turned-on and off in alternating turn-on and switch-off phases to power the LED light source via the secondary winding. SW1 is a field effect transistor, preferably a MOSFET. The transformer is SELV-rated. The sensing resistor may be a variable resistor to adjust the duration of the on/off phases to permit controlled dimming.