Research On High Voltage And High Efficiency Power Supply Control Chip

At present,switching power supply plays an irreplaceable role in electronic equipment due to its advantages of high efficiency and high reliability.With the development of soft switch technology,synchronous rectifier technology and digital control switching power supply technology,the power supply has a broader prospect.In order to cope with the high-voltage application environment in the industrial field,the semiconductor technology and manufacturing technology are constantly updated,so that the reliability of high-voltage power devices can be improved.Switching power supply is mainly composed of controller and power switch.The development of power devices is bound to promote the progress of control chip.The research on switching power supply control chip is indispensable in the development of switching power supply.In this paper,a PWM control chip is designed,which can be used in high voltage synchronous buck DC/DC converter.The dual outputs are phase shifted 180°,which can provide the electronic equipment for different power supply voltages.The chip contains a low dropout regulator,which can provide a stable low voltage power supply for the chip under the condition of high voltage input.In order to improve the conversion efficiency of DC/DC converter,a new current control mode of valley current sampling is proposed,which can not only enhance the anti-noise ability of current sampling,but also reduce the extra loss.In addition,the combination of PWM modulation mode and PSM modulation mode can make up the deficiency of single modulation mode and ensure the efficiency in light load and heavy load.Morever,the integrated driver on the chip meets the technical requirements of synchronous rectification and reduce the conduction loss.In this paper,firstly,the research background and significance of switching power supply were illustrated,and the research framework and work content were clarified.Secondly,the working principle,modulation mode and control mode of buck DC/DC were discussed.Then based on the theoretical basis of the control chip circuit design and simulation,the selection of chip peripheral components in practical application was studied.And the simulation circuit was built to simulate the system function parameters.Finally,the layout design of the chip was discussed,and the function of the chip was verified by further post-simulation.Based on the Dongbu 0.18μm BCD process,the circuit design and simulation of the control chip was completed using the Cadence Spectre tool.The main circuit modules in the chip were analyzed,including power circuit,oscillator circuit,error amplifier circuit,PWM comparator circuit,current sampling circuit,slope compensation circuit,drive circuit and protection circuit.The control chip designed in this paper works in a fixed frequency mode with a typical working frequency of 600kHz.The input voltage range is 6.5V-20V.The highest working temperature is 150℃.The control chip is applied to the buck DC/DC converter.The simulation results show that the output voltage ripple is within 30mV and the load adjustment rate is less than 0.01V/A.The loop stability is good,and the DC/DC conversion efficiency is 92%.The total layout area is 2650*2150μm~2.From the simulation results,it can be seen that the high-voltage and high-efficiency switch power supply control chip designed in this paper can well control the buck DC/DC to result stable voltage output,and all the indicators meet the design requirements.