Abstract: Disclosed are control circuits capable of auto-configuring two LED arrays either in parallel when the two LED arrays are operating off of 100±20% V AC voltage sources or in series when the two LED arrays are operating off of 200±20% V AC voltage sources according to the detection of the AC input voltage magnitude. The disclosed control circuits, ruling over the parallel or series configuration of the two LED arrays, could be implemented in discrete forms or as integrated circuits (IC).

Abstract: An ac-powered LED light engine coupled between a rectifier and a plurality of extrinsic LED sub-arrays is provided. The ac-powered LED light engine comprises a plurality of normally closed bypass switches, a normally closed current regulator, and a plurality of switch controllers. Each of the normally closed bypass switches is connected in parallel with a corresponding LED sub-array except for the topmost or the bottommost LED sub-array and shuttles between three switch states: ON, REGULATION, and OFF. The normally closed current regulator is coupled to the normally closed bypass switches and used to regulate the highest LED current level near the peak of an extrinsic mains voltage. Each of the switch controllers is coupled to a corresponding bypass switch as a feedback network and takes control of the three switch states according to a corresponding current sense signal.

Abstract: Disclosed are electronic control gears for LED light engines able to improve power factor by way of gearing up or down the LED current and the AC input current in response to and in synchronization with the AC input voltage. Moreover, the disclosed electronic control gears could further reduce flicker phenomenon and total harmonic distortion when used in collocation with disclosed valley fillers, filling the LED current valleys only during the dead time, and in conjunction with disclosed dummy loads, ramping up or down the AC input current only during the dead time.