A lighting unit (100) includes light emitting diode (LED) modules (120, 300) and a lighting driver (110, 200) connected to the LED modules. Each LED module includes LEDs (323) and an identification current source (324) supplying an identification current to an identification current output node (180, 380). All of the identification current output nodes are connected together to supply a total identification current having a magnitude which changes in response to the number of LED modules that are connected to the lighting driver. The lighting driver includes: a controllable current source (220 & 250) to supply an LED driving current to the LEDs of the LED modules, and a controller (230) that responds to the total identification current to control the controllable current source to supply the LED driving current at a magnitude which changes in response to the number of LED modules that are connected to the lighting driver.