Abstract: An AC light system with a control unit for controlling power of an LED is disclosed. According to one embodiment, a driver circuit for driving LEDs has a plurality of current sinks, a first interface configured to receive an AC power from an AC power source, a second interface to a plurality LED groups. The driver circuit further has a third interface configured to receive a control input from a control unit. Each current sink of the plurality of current sinks controls an LED current flowing through a corresponding LED group based on the control input from the control unit.

Abstract: An AC direct driver lighting system including a surge protection circuit and a current limiting circuit is disclosed. According to one embodiment, the AC direct driver lighting system includes an LED load, a rectifier, and an LED driver configured to receive rectified AC voltage from an AC power source and drive the LED load. The AC direct driver lighting system further includes a surge protection circuit and a current limiting circuit disposed between the AC power source and the LED load. The surge protection circuit and the current limiting circuit suppress excessive current flowing through the AC direct driver lighting system.

Abstract: An AC direct driver lighting system is disclosed. According to one embodiment, the AC direct driver lighting system includes a plurality of LED groups serially connected to an AC power source, and an AC driver comprising a plurality of current sinks. Each of the plurality of current sinks is connected between a respective LED group of the plurality of LED groups and a ground. The AC direct driver lighting system further includes a valley fill circuit coupled to a target LED group of the plurality of LED groups. The valley fill circuit charges from the AC power source and supplies electrical power to the target LED group via a current path established between the AC power source and the ground via at least one of the plurality of current sinks.

Abstract: An AC light system with a control unit for controlling power of an LED is disclosed. According to one embodiment, a driver circuit for driving LEDs has a plurality of current sinks, a first interface configured to receive an AC power from an AC power source, a second interface to a plurality LED groups. The driver circuit further has a third interface configured to receive a control input from a control unit. Each current sink of the plurality of current sinks controls an LED current flowing through a corresponding LED group based on the control input from the control unit.

Abstract: A driver circuit for driving light emitting diodes (LEDs). The driver circuit includes: a string of LEDs divided into n groups, the n groups of LEDs being electrically connected to each other in series, a downstream end of group m?1 being electrically connected to the upstream end of group m, where m is a positive number equal to or less than n. The driver circuit also includes a plurality of current regulating circuits, each of the current regulating circuits being coupled to the downstream end of a corresponding group at one end and coupled to the ground at the other end and including a sensor amplifier and a cascode having first and second transistors, each sensor amplifier being coupled to a different voltage source for providing a different reference voltage thereto.

Abstract: A driver circuit for driving light emitting diodes (LEDs). The driver circuit includes: a string of LEDs divided into n groups, the n groups of LEDs being electrically connected to each other in series, a downstream end of group m?1 being electrically connected to the upstream end of group m, where m is a positive number equal to or less than n. The driver circuit also includes a plurality of current regulating circuits, each of the current regulating circuits being coupled to the downstream end of a corresponding group at one end and coupled to the ground at the other end and including a sensor amplifier and a cascode having first and second transistors, each sensor amplifier being coupled to a different voltage source for providing a different reference voltage thereto.