Design Of BOOST Circuit For Operating At Ultra-low Voltage

With the rapid development of science and technology today,portable electronic products such as battery-powered mobile phones have shown explosive growth.Portable electronic products have developed in the direction of small size,light weight and strong endurance,so they are small in size,low in power consumption and The switching power supply with high conversion efficiency came into being.In order to prolong the use time of the product,it is necessary to ensure that the power management chip can still be used when the voltage is reduced to a certain level.Therefore,this article takes a low starting voltage as the goal to study and design the Boost-type DC-DC switching converter.First,the thesis analyzes the structure,principle,feedback mode and switching control method of the Boost switching converter.According to the advantages and disadvantages of each mode and application requirements,the PWM modulation method in the peak current feedback mode is finally selected;then,the loop is stabilized.The performance is analyzed in detail,and the zero and poles of the right half of the system phase complex plane are compensated by the average state space method to stabilize the system;then,the overall system framework and chip of the Boost boost circuit are designed according to the goal of low-voltage startup Peripheral topology and design and simulation of the required functional modules;finally,based on the Hua Hong Hongli(HHG)0.35μm BCD process device model,a specific circuit design was carried out,including band gap reference source,high voltage LDO,and voltage discrimination circuit,voltage selection circuit,error amplifier,comparator,oscillator,slope compensation circuit,soft start circuit and over-temperature protection circuit,etc.Through the application of the key design technology of the auxiliary oscillator,the design difficulty of the normal startup of the system under low operating voltage is solved;at the same time,in order to prevent the excessive surge current in the early stage of the system startup,this paper adopts the output voltage of the clamp error amplifier.In this way,a soft start circuit is designed to suppress the effect of large inrush current.Use Cadence software to carry on the overall simulation verification to the low-voltage start-up Boost boost circuit designed in this paper,and analyze the simulation results.The simulation results show that the low-voltage start-up Boost boost circuit designed in this paper can work normally in the input voltage range of 1.2V to 5V,and the output voltage range is 1.4V to 16 V.Under typical application conditions,if the output voltage value is equal to 10 V,at the same time When the load current is200 m A,the conversion efficiency is the highest at this time,the conversion efficiency is 84.5%,and the voltage ripple rate is less than 0.3%.The result shows that the ultra-low voltage boost circuit designed in this paper has reached the required design index.