A 26 W 97%-Efficiency Fast-Settling Dimmable LED Driver With Dual-nMOS-Sensing Based Glitch-Tolerant Synchronous Current Control for High-Brightness Solid-State Lighting Applications

Abstract

This paper presents an integrated buck-type dimmable synchronous LED driver for high-brightness solid-state lighting applications. A glitch-tolerant synchronous current control (GT-SCC) scheme is proposed to regulate the average LED current. The GT-SCC enables fast settling time of the LED current upon start-up or PWM dimming condition, and provides reliable operation under high dV/dt slewing during switching transitions of the LED driver. The proposed LED driver consists of a high-speed low-power HV synchronous gate driver to enable on-chip synchronous rectification with a dual-nMOS power train under different input voltages for the conduction power loss reduction. Two on-chip senseFET peak and valley current sensors are also developed to offer low-power and reliable current sensing under high input voltages. Implemented in a 0.35 $\mu$ m 50 V CMOS process, the proposed LED driver supports a wide input range from 5 V to 45 V, operates up to 4 MHz with a small-value inductor of 8.2 $\mu$ H, handles a high PWM dimming frequency of 20 kHz with a wide duty-ratio range from 0.1 to 1, and delivers an average LED current of 700 mA for driving up to 12 series-connected HB-LEDs (with the maximum output power of 26 W). The proposed LED driver achieves a peak power efficiency of 97.2% and the current deviation ${\leq}{\pm} $ 3.3% of the average LED current under different conditions. The worst-case settling time achieves 3.2 $\mu$ s that is at least 2.7 times improvement over state-of-the-art counterparts.