An LED dimmer for connection between an LED driver and an LED arrangement, comprising: - an input for receiving an input signal being one of a constant current, a constant voltage being above an operating voltage of the LED arrangement or a constant voltage being below the operating voltage of the LED arrangement from the LED driver; - a means for determining whether the input signal is one of the constant voltage being above the operating voltage of the LED arrangement, the constant voltage being below the operating voltage of the LED arrangement or the constant current from the LED driver; characterized in that the LED dimmer further comprises: - a converter circuit being operable as a boost converter and as a buck converter, wherein the converter circuit is arranged to provide voltage up conversion when being operated as the boost converter dependent on a required dimming level and to provide voltage down conversion when being operated as a buck converter dependent on the required dimming level; - a controller for controlling the converter circuit in dependence on the determination whether the input signal is one of the constant voltage being above the operating voltage of the LED arrangement, the constant voltage being below the operating voltage of the LED arrangement or the constant current; and - a first output for providing a drive signal from the converter circuit to a first terminal of the LED arrangement, wherein the controller is arranged to operate the converter circuit as to: provide in a first mode the voltage up conversion when the LED dimmer receives the constant current; provide in a second mode the voltage up conversion when the LED dimmer receives the constant voltage being below the operating voltage of the LED arrangement, and provide the voltage down conversion when the LED dimmer receives the constant voltage being above the operating voltage of the LED arrangement. - an input for receiving an input signal being one of a constant current, a constant voltage being above an operating voltage of the LED arrangement or a constant voltage being below the operating voltage of the LED arrangement from the LED driver; - a means for determining whether the input signal is one of the constant voltage being above the operating voltage of the LED arrangement, the constant voltage being below the operating voltage of the LED arrangement or the constant current from the LED driver; characterized in that the LED dimmer further comprises: - a converter circuit being operable as a boost converter and as a buck converter, wherein the converter circuit is arranged to provide voltage up conversion when being operated as the boost converter dependent on a required dimming level and to provide voltage down conversion when being operated as a buck converter dependent on the required dimming level; - a controller for controlling the converter circuit in dependence on the determination whether the input signal is one of the constant voltage being above the operating voltage of the LED arrangement, the constant voltage being below the operating voltage of the LED arrangement or the constant current; and - a first output for providing a drive signal from the converter circuit to a first terminal of the LED arrangement, wherein the controller is arranged to operate the converter circuit as to: provide in a first mode the voltage up conversion when the LED dimmer receives the constant current; provide in a second mode the voltage up conversion when the LED dimmer receives the constant voltage being below the operating voltage of the LED arrangement, and provide the voltage down conversion when the LED dimmer receives the constant voltage being above the operating voltage of the LED arrangement. - a converter circuit being operable as a boost converter and as a buck converter, wherein the converter circuit is arranged to provide voltage up conversion when being operated as the boost converter dependent on a required dimming level and to provide voltage down conversion when being operated as a buck converter dependent on the required dimming level; - a controller for controlling the converter circuit in dependence on the determination whether the input signal is one of the constant voltage being above the operating voltage of the LED arrangement, the constant voltage being below the operating voltage of the LED arrangement or the constant current; and - a first output for providing a drive signal from the converter circuit to a first terminal of the LED arrangement, wherein the controller is arranged to operate the converter circuit as to: provide in a first mode the voltage up conversion when the LED dimmer receives the constant current; provide in a second mode the voltage up conversion when the LED dimmer receives the constant voltage being below the operating voltage of the LED arrangement, and provide the voltage down conversion when the LED dimmer receives the constant voltage being above the operating voltage of the LED arrangement. provide in a first mode the voltage up conversion when the LED dimmer receives the constant current; provide in a second mode the voltage up conversion when the LED dimmer receives the constant voltage being below the operating voltage of the LED arrangement, and provide the voltage down conversion when the LED dimmer receives the constant voltage being above the operating voltage of the LED arrangement.