A Design Of LED High Voltage Linear Constant Current Driver IC

LED as a new generation of green light in the field of lighting,the penetration rate of LED lighting products is increasing year by year due to the rapid improvement of the performance-price ratio of LED lighting products.It provides high-efficiency and low-cost driver chips for LED lighting products,which provides the most powerful guarantee for the wide promotion of LED and replaces traditional lighting products.With the maturity of domestic ultra-high voltage BCD technology in recent years and the further improvement of chip packaging technology,most of the circuits of linear high voltage drive power supply can be integrated in the same chip,which realizes a simple and efficient photoelectric integrated lighting system and simplifies the process flow of lamps.The cost of this drive scheme is reduced by 30% to 40% compared with the traditional switching power supply.In recent years,the driving force of lighting products is mainly from the bulb,lamp and other alternative light source products,price and cost will become the key to customers’ consideration.Due to cost factors,The power supply solution based on linear IC constant current source has gradually become an acceptable product..Based on this demand,this design chooses the research direction of high voltage single linear constant current driving chip.Taking into account the impact of surge peak voltage on the life of LED lamps,the chip withstand voltage is raised to 700 V.The internal circuit of the chip does is independent power pin.The high voltage JFET integrated with the 700 V LDMOS driver and the Zener diode generate the power for the internal circuit.The linear constant current LED drive circuit uses the negative feedback method to control and adjust the resistance of the tube to realize the constant current operation of the LED.The chip is designed and manufactured based on Huarun CSMC Technologies Corporation CSMC₁um₇00V_BCD technology.In this paper,a variety of LED drive technologies are studied in depth,and the single-channel linear constant current technology with external power supply,single-channel linear constant current technology without external power supply and piecewise linear constant current technology without external power supply are compared.The single-channel linear constant current driving mode without external power supply is determined,Then the single-channel linear constant current drive technology without external power supply is studied,and the basic working principle of the LED drive system and the basic parameters of the chip are given.Then the overall structure and working principle of the drive circuit are introduced,The bandgap reference circuit with temperature compensation is introduced in detail.Only two transistors are added to the bandgap reference circuit to protect temperature and enhance the effect of overtemperature protection,and the high-voltage constant-current drive circuit with temperature compensation is designed,when the chip junction temperature rises to 110 degrees,the output current parameters are decreased rapidly.improve the reliability of the circuit.In this paper,based on the set of indicators,complete the overall circuit design,simulation,so that the indicators meet the design requirements.At the same time,the layout design and verification of each module circuit and the whole circuit are completed.