Dimmable LED Lighting Circuits, Controllers therefor and a Method of Controlling a Dimmable LED Lighting Circuit

摘要

Controllers (360, 360'), lighting circuits and methods are disclosed, for a dimmable LED lighting circuit having a series arrangement of two types of LED, the controller comprising a control circuit (330), a bypass circuit (340) and optionally a further bypass circuit and being operable for controlling a current, the current (Idriver) being separable into first and second parts (I W , I B ), and into further first and second parts, wherein the controller is configured to direct the (further) first part through the LED or LEDs of the second (first) type and direct the (further) second part through the (further) bypass circuit (respectively), and wherein the control circuit is configured to adjust the ratio between the first, or further first, part and the second, or further second respectively, part in dependence on a dimming level of the LED lighting circuit.