A light generating device (20) comprises: —an input for receiving a DC input voltage (Vin) of varying magnitude; —a controllable current source (40); —a switch matrix (30) comprising a plurality of controllable switches (S1-SN); —a plurality of n LEDs (D1, D2, . . . Dn) connected to output terminals of the switch matrix (30); —a controller (50) controlling said switches and controlling the current generated by the current source dependent on the momentary value of the DC input voltage (Vin). The controller is capable of operating in at least three different control states. In a first control state all LEDs are connected in parallel. In a second control state all LEDs are connected in series. In a third control state at least two of said LEDs are connected in parallel while also at least two of said LEDs are connected in series.