A Compact Modular CMOS WLED Driver for Multi-Display Applications

Abstract

This paper presents a WLED driver solution for multi-display screen systems. The proposed solution features a single-inductor power stage with independent outputs; each display has multiple WELD strings with independent digital brightness/dimming control. The inclusion of high-side switches at the output terminals enables independent output voltage control and seamless display module activation/deactivation with minimized power consumption. The proposed circuit solution is designed and simulated using TSMC 40 nm technology with a digitally rich implementation that may easily scale to any node process. A three-display system, each with three strings with 6 WELDs, is utilized to demonstrate the efficacy of the solution and verify the functionality of the system. The system is driven by a single battery with a 3.2-4.2 V range and uses a 1 MHz switching frequency clock. The output voltage of the three modules can be configured independently from 7 V to 30 V with a common overvoltage protection circuit.