High Efficiency 1.2MHz Step-up DC-DC Converter Chip Desig

With the rapid development of science and technology,portable electronic devices have become an indispensable part of people’s lives.As the energy source of electronic devices,power management chips have attracted much attention because of their small size,high conversion efficiency,wide voltage regulation range and other advantages,and have become one of the research hotspots in the field of integrated circuits.In this paper,the basic principle of boost DC-DC converter,feedback control mode,modulation mode and inductor current conduction mode are deeply analyzed.A power chip of boost DC-DC converter with constant frequency and high efficiency current mode control is designed,which has embedded compensation,soft start circuit and various protection circuits,so as to improve the service life of the chip.The PWM/PSM hybrid modulation mode was used to automatically switch to PSM mode under light load,so as to improve the conversion efficiency of the system in a wide range of load.According to the expected parameter requirements,the overall circuit block diagram is designed,and the key modules such as reference circuit,error amplifier,current sampling circuit,oscillator,soft-start circuit,over-temperature protection circuit,under-voltage protection circuit are designed and optimized.Based on SMIC 0.18μm BCD technology,the whole circuit structure and function are designed by Cadence software,and the whole circuit is simulated and verified by Spectre.Finally,the whole layout is completed.The input voltage range is:3 V to 5 V,the typical output voltage is 5 V,the highest output voltage is 12 V,and the switching frequency is fixed to 1.2 MHz.The simulation results show that under the typical application conditions of V_in=3.7 V,V_out=5V,L=4.7μH,C_in=10μF,C_out=22μF,the load adjustment rate is less than 10%/A.Linear adjustment rate<5%/V;When the load current ranges from 0 to 500 mA,the conversion efficiency can reach 90%.