As the Internet of Things (IoT) continues to proliferate, connected and smart
solutions are influencing more and more areas of our lives, as well as lighting
sector. From system point of view, the additional smart features will require
separate power and voltage domains from LED load, therefore, integrating an
auxiliary (AUX) power supply into LED drivers is an ideal option to facilitate LED
luminaire system design and reduce system cost and complexity. In this paper, a
cost effective architecture based on Flyback topology is proposed for both constant
current (CC) output for LED drive and constant voltage (CV) output for AUX supply.
A novel nonlinear ramp based control scheme is proposed to decouple the main CC
power train from the CV AUX supply and avoid LED output flickering. Small signal
modeling is presented to highlight the advantages of this control scheme over
conventional peak current mode control. This scheme has been implemented
successfully for a 40W dimmable LED driver with a 12V 3W AUX supply.