Multi-mode Dc-dc Converter Efficient Mode Switching Technology Research

As the financial tsunami receded, the global semiconductor market has gradually recovered. China has become the world's largest semiconductor market. And power management IC market will rapidly expand in the next few years. As every country around the world is actively considering how to improve energy efficiency, the research that how to improve power management efficiency of the PMIC becomes very urgent.Based on the analysis of mode switching technology,this paper designed multi-mode DC-DC Buck converter chip with the 90nm 1P7M CMOS process,and focused on switching between the modulation modes. Input voltage range of the chip is from 2.7V to 4.2V,the output voltage is from 0.8V to 1.5V dynamically adjustable, controlled by the result of the built-in DAC,whose step is 25mV.The chip's switching frequency is 2MHz, the load current capacity is 1A, and the chip can work in the temperature range from -40℃to 125℃. There are PSM and PWM mode in the chip system, which ensures the system has a high conversion efficiency during the entire load range, PWM modulation mode includes CCM and DCM modes. The chip has soft-start function, over-temperature protection, over-current protection and under-voltage protection. Synchronous rectification and voltage feed-forward technology are also used in the chip. Synchronous rectifier can improve the efficiency of the converter, and voltage feed-forward can improve transient response rate while input voltage changes. The dead-time control module also ensures that the main switch and synchronous MOSFET won't conduct at the same time. The segment-drive of the power MOSFET can improve the efficiency under light loads. This thesis gives the simulation results, which shows the chip performs well. The layout design and test results of the chip are also included.This paper firstly introduced the basic principles of DC-DC converter. Secondly, described the system and mode-switching design of the converter chip, then introduced the design of the key modules in the converter circuit, including the principle of the circuit, using HSPICE for the functional verification and performance parameters simulation. At last, Stated the top level simulation of the converter chip, layout design and chip test.