A $V_O$-Hopping Reconfigurable RGB LED Driver With Automatic $\Delta V_O$ Detection and Predictive Peak Current Control

Abstract

A cost-effective single-converter reconfigurable CMOS LED driver is proposed to accurately and adaptively bias RGB color LEDs. An automatic ΔV _O detection technique is developed to precisely detect the voltage difference between the red and green/blue LEDs regardless of the PVT variations. The fast VO-hopping technique is also implemented to instantaneously adjust the output voltage level, achieving 198 ns/V VO-hopping speed on 0.35 μm CMOS. This is at least one order faster than the state-of-the-arts. Predictive peak current control and burst-mode operation are employed for fast inductor current modulation and robust operation. The switching frequency is stabilized around 1 MHz by an adaptive off-timer for switching noise spectrum control. The proposed driver consumes 8.6 times less headroom power than its fixed-output counterparts. The performance has been verified by measurement results of a 0.35 μm CMOS prototype.