Research And Design Of Current Mode Buck DC-DC Switching Converter

As an important part of electronic products,power management chips are the link for power supply in electronic products.The chip can convert the energy of the external power supply to each module inside the electronic product to meet the power demand of the internal module.At the same time,to ensure the safety of electronic products,the power management chip should also have detection and protection functions.With the rapid development of emerging application fields such as the Internet of Things(Io T),Artificial Intelligence(AI),and new energy,electronic devices have put forward higher requirements for the performance of power management chips.Therefore,it is particularly important to design a multi-mode,high reliability,high efficiency,and high conversion rate DC-DC power chip.Based on the above requirements,this article designs two Buck-type DC-DC power chips:1.This paper designs a PWM-controlled peak current-mode DC-DC converter chip.When the chip is stable,it automatically works in PWM mode;in order to reduce the complexity of the system compensation network,the power chip uses a current-mode PWM control scheme.The error amplifier with high gain and large slew rate is used inside the system to improve the response speed of the circuit during transient changes.At the same time,a high-precision current sensing circuit is designed to improve the accuracy of the output voltage;In addition,the drive circuit is optimized to improve the working efficiency of the chip.The chip adopts 180 nm BCD process,it's input voltage is 4V-6V,output voltage is3.3V,and the maximum load current can reach 0.8A.When the load current changes between0.8A-0.2A,the response time is less than 20?s.2.This paper designs a DC-DC converter chip controlled by Current Mode Adaptive on Time(CM-AOT).The converter improves the traditional valley current mode constant on time(COT)control scheme,and further improves the working performance of the chip.The compensation circuit in the DC-DC converter can increase or decrease the on-time correspondingly when the load changes suddenly to speed up the system transient response speed;Since the on-time changes only when the load changes suddenly,the structure still meets the small signal model of the traditional COT structure;when the system is in a steady state,the converter's operating frequency is not affected by changes in the input voltage and output voltage.In addition,the valley current comparison module designed in this article can accurately sample the inductor current,which greatly improves the stability of the system.The input voltage of the converter is 6V-20 V,the output voltage is adjustable from 0.6V-5V,the operating frequency can be adjusted within 0.5M-2MHz,and the maximum operating current is 3A.When the load current changes between 3A-0.5A,The response time is about10?s,and the maximum work efficiency can reach more than 90%.The chip is designed using 180 nm BCD process and will be taped out soon.