Patent ID: 9504109
Filing Date: 2016-11-22
CPC Classification: H05B

Claim Text:
1. An alternating current (AC) lighting system comprising: a plurality of LED groups serially connected to an AC power source; an AC driver comprising a plurality of current sinks, wherein each of the plurality of current sinks is connected between a respective LED group of the plurality of LED groups and a ground; and at least one valley fill circuit coupled to a target LED group of the plurality of LED groups, wherein 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, wherein each of the plurality of current sinks includes a cascode circuit comprising a first transistor and a second transistor connected in series, wherein the first transistor is provided with a fixed voltage and the second transistor is controlled by a sensor amplifier that compares a reference voltage level and a voltage level at a downstream of the cascode circuit, and wherein a first reference voltage level applied to an upstream sensor amplifier of the plurality of current sinks is lower than a second reference voltage level applied to a downstream sensor amplifier of the plurality of current sinks.