Sectional linear LED driver for optimised efficiency in lighting applications

A novel sectional linear driving method for light-emitting diode (LED) driver is studied. Considering several issues to be concerned in LED lighting applications, a complete introduction and analysis of the technique is proposed in this study. As the performance of the sectional linear LED driver can be affected by the LED distribution in each LED sub-string, a behavioural model is established to guide the design. Simulation results are obtained by utilising the behavioural model to optimise the output power and efficiency. The LED driver is fabricated with a 1 µm 5 V/20 V/500 V BCD technology, and a 15-W T-8 LED tube light prototype is established on the basis of the driver IC. A series of experiments are conducted to verify the theoretical analysis and the accuracy of the proposed model. The experimental data agrees with the simulation results, above 0.9 power factor (PF) and 90% efficiency are achieved with few peripheral components based on the design guidance made by the proposed model. Both the driving technique and the behavioural model are believed to be useful in the high efficiency, high PF, and cost-effective ac LED lighting applications.