Self-oscillating Buck Converter LED Driver with Indirect Inductor Current Reconstruction

Abstract

In this work, a blocking-diode self-oscillating buck converter (SOBuC) is proposed to meet the demand for high performance LED drivers. For robustness and tight LED current regulation, multiple closed loop controls such as indirect inductor current reconstruction using offline PWM controller and peak current control using a common comparator were proposed and implemented. To cater for the lost signal during indirect inductor current reconstruction, control adjustments were made, and other strategies were proposed. The desired transient/steady state performance verified via simulation yielded a maximum efficiency of 94.8% and 2.7% LED current ripple factor.