Abstract: A constant current LED driver comprising an LED driver to supply constant current to an LED circuit provided with a protection element, an open loop sensor to sense the open loop of the LED circuit and a clamping control to maintain the voltage in the LED circuit at a predetermined level. The open loop sensor may be a high voltage detector. The clamping control controls the power supplied to the LED circuit in response to the detection signals of the open loop sensor. In one embodiment, the clamping control controls the power supplied to the LED circuit according to the power of the detection signals.