With An Automatic Restart Function, Dc-dc Converter Control Circuit Design

This thesis was supported by the Key Program of National Natural Science Foundation of China. The thesis studied the design of a DC-DC switching converter with Auto-restart function. A new modulation mode named Pulse-cycle Skip Modulation (PSM) and current limit state machine were designed. Moreover,weak EMI characteristics had been realized by applying frequency jitter. The converter had the virtues of high integration level, high efficiency, high reliability and low cost. It can be formed high efficiency power supply by using a few external components. The basic design index was: maximum output power 9W, no load consumption < 50 mW , switching frequency 132KHz , maximum duty cycle 65% , thermal shutdown temperature 135℃.Simulation is very important to analog IC design. Though the precision of circuit simulation result is limited by the simulation tools,the precision of the device model is the primary factor. The thesis discussed a parameter extraction program for the MOSFET LEVEL1 model.In the analysis and design of circuit,at first,the thesis described the system function of the new DC-DC switching converter. Then several sub-circuits of converter IC such as oscillator, over-temperature shutdown circuit, auto-restart counter circuit and control circuit were completely discussed. Oscillator generated a wave with frequency 132 KHz as the clock signal. Over-temperature shutdown circuit made the main circuits shut down in the condition that the temperature of chip was over 135℃. . Auto-restart counter circuit made the circuits to be controlled perfectly.Layout design and DRC,LVS verification had been finished by applying EDA tools CADENCE after the analysis and simulation of the whole chip.The circuit design,simulation, layout design and layout verification had been finished.