Dimmer compatible light emitting diode driver

Abstract

Drivers () for driving lamps () comprising light emitting diodes are provided with arrangements () for, in response to detections of instantaneous values and average values of input voltage signals, providing output currents. Detected instantaneous values divided by detected average values form ratios. Adaptation circuits () for adapting some ratios make the drivers () dimmer compatible. The adaptation circuits () may comprise first circuits (-) for adapting the detected instantaneous values, second circuits (-) for adapting the detected average values, and third circuits (-) and fourth circuits (-) for respectively modulating the detected average and instantaneous values to add bleeder functions. The adaptation circuits () may adapt the ratios in different ways during different parts of a period of the input voltage signal and such that a time-interval, during which time-interval an input current signal of the driver () has instantaneous values larger than a threshold, is increased.