A device includes a voltage regulator, circuits, and a current bus. Each of the circuits includes at least one LED driver. The voltage regulator supplies electrical energy to a plurality of LED groups. Each of the circuits includes a voltage measuring circuit for detecting voltage drops across the LED drivers. The LED drivers set the currents through the LED groups. Each of the circuits includes a local controller. The local controller withdraws a current from the control bus in dependence on the detected voltage drops of the LED drivers included in the circuit. A bias current source injects a bias current into the control bus. The control bus sums the currents in the current bus. The output of the regulator is controlled based on the summed current.