Fully Integrated Reconfigurable Constant Current LED Driver for Adaptive Input

The development of high-efficiency LED drivers has shifted toward inductor-less architectures, eliminating bulky passive components while ensuring optimal performance and power factor correction. This paper presents an inductor-less LED driver that dynamically regulates LED current based on input voltage variations. The proposed circuit employs a stepwise phase activation mechanism, where LED conduction phases are sequentially enabled according to the rectified AC input voltage, ensuring optimized power distribution. A multilevel reference voltage (Vref) generation technique is integrated, which dynamically adjusts Vref values to regulate LED drive current, thereby stabilizing power output under fluctuating input conditions. The design is implemented using the XFAB 0.18 μm CMOS process, with simulations performed across input voltages of 45 V, 55 V, and 65 V. The results demonstrate that the driver achieves a peak efficiency of 93.59%, with an adaptive current control mechanism ensuring a constant 4 W power output while maintaining a high power factor. By combining current regulation with a Vref-driven dimming strategy, the proposed circuit offers enhanced energy efficiency, stable operation, and reduced circuit complexity, making it a suitable alternative to traditional switched-mode LED drivers for various lighting applications.