Current-mode Dcdc Buck Regulator Chip Research And Design

Power is the heart of electric equipment. With the development of electric technology, more and more portable electric production come into our life and become a port of daily necessity. Because of the characteristic of portable production are small sizes, stable operating status and staying use time. Battery requests much high performance. So the Switch Mode Power Supply market becomes larger year by year. The circuit designed in this graduation thesis:current mode BUCK DCDC converter IC is widely used in 2.5～5.5V portable battery application.This IC integrates a power switch MOSFET inside. It can regulate output voltage from 0.6V to max input voltage continuously. It has an automatic dual mode regulating function of PWM mode for heavy load and PFM mode for light load. Also it has the function of protecting over-current, over-temperature, has a fixed 1.5Mhz of operating frequency, so the chip can constitute a reliable BUCK DCDC converter with only a little of external components. In normal operating condition, the converting efficiency all can reach above 80%.This thesis firstly expounds the theory of Switch Mode Power Supply, analyzes the critical technique of BUCK DCDC converter. Then it introduces and analyzes some critical modules carefully, give the result of simulation which verified the feasibility and validity of design plan. This design use CSMC 0.5μm DPTM process, also analyze the critical issue of layout. Finally we sum up the design result and existing issue.