On-chip boost DC-DC converter in color OLED driver & controller ICs for mobile application

On-chip boost DC-DC converter used in color OLED driver and controller ICs for mobile application is presented in this paper. For special systematic requirement, current-limited pulse-frequency modulation (PFM) control scheme is used. This converter is designed with 0.35/spl mu/m 1P4M high-voltage CMOS process. Experimental results show that, the converter can operate with supply voltage from 2.5 to 4.2V, which is suitable for single-cell lithium-ion rechargeable battery supply application, and boost voltage up to 12/spl sim/18V for illuminating OLED display pixels. The output ripple voltage is about 250mV with 6.8/spl mu/F off-chip capacitor and 10/spl mu/H off-chip inductor. The power efficiency is over 75% for 1/spl sim/300mA load current, maximum to 87% at about 200mA load current.