Design Of Current Mode BUCK DC-DC Switching Power Supply With Digital Programmable Function

The rapid promotion of portable devices such as smart phones and wearable devices has driven the rapid development of power management systems.BUCK DC-DC switching power supplies are widely used in power systems with their high conversion efficiency.For the traditional analog power supply,the circuit cannot be changed after it is completed,and it can only be applied to a specific circuit;the digital power supply has a long development cycle,high cost,and is difficult to design.This paper introduces a BUCK DC-DC switching power supply design with digital programmable function and analog loop control.It can combine the advantages of digital power supply with parameters that can be programmed online with the advantages of analog power supply with simple control loop and easy design.Increased flexibility in switching power supplies and shortened development cycles.Firstly,the paper briefly introduces the switching power supply and analyzes its development trend.Among them,digitization and multi-purpose are the characteristics of the switching power supply designed in this paper.Next,the basic principle of BUCK DC-DC switching power supply is analyzed.Including topological structure,control mode and modulation mode,the current control mode and its three implementation methods are analyzed in detail.Then the system designed in this paper is introduced as a whole,including the realization of digital programmable circuit and loop modeling.And simulation,introduces the digital programmable parameters and implementation methods,and models the whole circuit designed in this paper.The simulation results show that the circuit can work normally and stably.Next,the principle analysis and simulation verification of the key sub-modules in the circuit are carried out.It mainly includes bandgap reference,error amplifier,PWM comparator,temperature detection and other modules;finally,the application topology of the whole system is simulated to verify the performance parameters of the system.The switching power supply can transmit data through the PMBus bus,and the user can program the application parameters online and collect the working data of the power supply in real time.The basic principle is: when the power supply starts working,the system reads the corresponding parameter configuration from the EEPROM to make the circuit work stably.When the user needs to adjust a certain parameter of the circuit,the data is transmitted to the EEPROM through the PMBus,and then the power is applied again.The new configuration achieves the purpose of online programming.The control loop of the power supply uses the control method of the peak current mode to achieve stable operation of the circuit.Based on the HHGrace 0.18 um BCD process,the sub-module and overall circuit of the design are verified by Spectre platform and Hspice platform.The simulation results show that the output voltage can be stabilized at 1.5V,2.4V,3.3V when the input voltage is 12 V.At the same time,the output voltage can be modified during operation and can work stably under different output voltage conditions.The load regulation rate and linear adjustment rate are both less than 1%,which meets the design requirements.