Design Of BOOST DC-DC Converter With Peak Current-mode PWM Control

With the rapid development of electronic technology in 21st century, power management IC has been widely used in the area of communication network, computer and automobile electronics. Enlightened by the merit and wide market of thin-film transistor liquid-crystal display (TFT-LCD) and supported by the research item of institute of electronic CAD-"Theoretical research and design of key techniques for mixed signal IC"of Xidian University, a low cost, highly integrated, and multiple-output power management controller, XD0804, is designed. XD0804 can generate all the supply rails for TFT-LCD panels in TVs and monitors operating from a regulated 12V input. It integrates a BUCK DC-DC converter and a BOOST DC-DC converter, a positive and a negative charge pump, two operational amplifiers and a low drop-out regulator. The author is in charge of the design of the BOOST DC-DC converter block integrated in XD0804.This paper analyzes the related theories of BOOST DC-DC converter detailedly. This BOOST DC-DC converter block designed employs a fixed-frequency, peak current-mode PWM architecture and provides fast-transient response to pulsed loads of TFT-LCD panel source drivers. The design process is presented. The integrated MOSFET and built-in digital soft-start function reduce the number of external components required while controlling inrush currents. To avoid the current loop instability, a simple linear slope compensation circuit is designed and combines with a novel voltage to current converter to implement adding with sensing current. Meanwhile, according to the characteristic of the power MOSFET integrated, a simple current sensing circuit is designed.The sub-blocks and the whole circuit of the BOOST DC-DC converter block are designed based on the 0.6μm 20V BCD process. And its function and performance of the whole circuit have been verified by Cadence and the results have met the requirements expected.