Design Of A High Precision Primary Side Feedback Constant Current Driving Chip

In recent years,lighting electricity accounted for the proportion of the total electricity is increasing year by year,as of November 2016,lighting electricity accounted for about23%of total electricity,lighting electricity is the basic demand for power,how to save energy and protect environmentwill naturally become the topic in lighting.Under the concept of energy saving and environmental protection,the advantages of LED lighting compared to the traditional lighting have gradually emerged,so the development of LED has become a hot spot in recent years.it's luminous intensity is determined by the strength of the drive current,which affects the life of the current,small current affects the brightness,while the constant current driver chip as the key part of the drive of LED,the main function is to provide the stable and reliable driving current,its performance has a direct impact on the stability of LED,Therefore,the research on the constant current drive chip has a very important significance and value in the field of LED lighting.According to the architecture design and key technology of high precision for driving LED for the study,to complete the chip which can provide high precision drive current,In this paper,based on the analysis of the characteristics of LED and the existing driving technology and the stability of the power market,we presents a low power,high precision constant current driver chip for driving LED based on the original side feedback technology.The whole driver chip includes the reference module,the current sampling module,the voltage compensation circuit and so on.Taking into account the voltage after rectification of approximate value of DC is still relatively high,so the reference module using low pressure pipe and high pressure pipe stacked,which can save chip area and keep output bandgap voltage accuracy,The primary peak current detection module in line voltage compensation circuit using a new type of circuit has the patent structure,compared with the traditional line voltage compensation structure,this paper design increased the precision of line voltage sampling circuit,greatly improves the linear adjustment rate.the traditional approach end point of information was compared by point pressure degaussing voltage and the reference voltage points determine the degaussing time,this structure increases chip area at the same time also affect the static power system,and reduce the end point detection accuracy of degaussing.In contrast to the new structure detection,firstly,the voltage difference is amplified,and then compared with the reference voltage,the detection accuracy of the end point of the demagnetization time is greatly improved.The innovation of the above part of the module structure to improve the output current accuracy.In addition,the chip also has the function of over temperature protection,short load/open circuit protection and greatly enhance the market competitiveness.In this paper,the original side feedback technology of high-precision constant current driver chip based on CSMC 0.8um BCD technology to achieve,the supply voltage of 85V~265V AC,chip using Cadence HspiceD tools to complete the simulation.The simulation results show that the output current of the chip is less than?2.5%,the linear adjustment rate and the load regulation rate are less than?2.5%,and the conversion efficiency is more than 80%.In addition the chip protection function has been verified,complete the layout area of 1980×990um~2.The chip has been taped out and put into production.This paper relates to the theory and its important significance for the study of constant current driver,the design and Realization of the high precision primary side feedback technology based on constant current driver also has important commercial value and broad application prospect.