A New Single Inductor Bipolar Multiple Output (SIBMO) Boost Converter Using Pulse Frequency Modulation (PFM) Control for OLED Drivers and Optical Transducers

Chun-Kai Chang1,  Chung-Hsin Su2,  Yung-Hua Kao1,  Ming-Hung Yu1,  Thilo Sauter3,  Paul Chao1
1Department of Electrical Engineering, National Chiao Tung University, Hsinchu, Taiwan, 2Sitronix Technology Corporation, 3Center for Integrated Sensor Systems, Danube University Krems, Austria


This study proposes a single-inductor bipolar multiple-output (SIBMO) boost converter utilizing pulse frequency (PFM) control for organic light-emitting diode (OLED) drivers and optical sensors and transducers. The purpose of the converter is to simultaneously provide multiple voltage sources with opposite polarity to meet the requirements of various applications such as OLEDs or optical transducers. The bipolar voltage source is essential for the formation of alternating voltage to extend the lifetime of OLEDs. The converter boosts the input of 2.8 V to two positive outputs and two negative outputs, +12 V, +6 V, -12 V, and -6 V, respectively. Different from the commonly used pulse width modulation (PWM), the constant on-time (COT) approach is adopted herein with a dynamic charging algorithm to automatically verify the operating frequency, thus profiting from less circuit complexity, improvement of cross regulation, and high transfer efficiency in unbalanced load cases. While total maximum output power is 320 mW and the switching frequency varies from 650 kHz to 0 Hz, the maximum efficiency reaches 83.1% by simulation.