Research And Design Of LED Driver Integrated Circuit

The continuous innovation and development of science and technology promote human's exploration on light sources.LED light source is the most efficient artificial light source found so far.Owning the advantages of energy saving,environmental conservation,as well as longevity and so on,it has become the mainstream light source for various kinds of applications.With the increasingly complexity of LED application scenario,people's demand for LED function is getting bigger and bigger.However,the LED light source requires a specific drive control system to stabilize the work,which makes the circuit designers' s research on LED drive control system deepen gradually.In combination with the requirements of LED application functions and scenarios,this paper studies the implementation of two kinds of LED drive control,analog circuit and digital-analog hybrid.Firstly,a solar light string control chip XD861 A is designed,which supports the functions of LED constant light and flashing.The analog boost type conversion structure is used to realize the drive control of the battery for multiple sets of parallel LED light strings.In addition,from the perspective of popular digital circuits,a control chip XD9860 for single-line transmission of three-channel LED lamp bead is designed,which can be changed at any time by programming.The main research results of this paper are as follows: 1.In this article,a boost-driven architecture with constant on time control is designed.The low-voltage driving LED lamp string can be realized and the current of the LED string can be adjusted by driving the inductance outside the control chip.Meanwhile,overvoltage and undervoltage modules are built into the architecture to protect the chip from damage.2.In this article,a light control module and a charging control module are designed.It can automatically turn off the LED string during the daytime and automatically trun on the LED string at night to reduce the energy loss.At the same time,the solar panel can be controlled to charge the battery during the day.Since the input voltage of the driver chip is as low as 0.9V,the power requirements of solar energy battery can be effectively reduced.3.In this article,a flicker and flicker pulse width modulation module are designed.The mode control input can realize the selection of the constant light or flashing function.At the same time,according to the actual needs of the user,the time of turning on and off can be freely configured by selecting external resistors with different resistance values.4.In this article,a digital control chip with a single-wire transmission structure is designed.The data control information is carried in the power supply with return-to-zero code and directly input into the chip through the transmission protocol,while the output R,G and B drive the LED lamp bead to realize the color light control.The single-wire transmission protocol reduces the complexity of chip control,while the direct drive of the lamp bead is designed for cascading.5.In this article,an information decoding module is designed.It can anslyze the address information and conctrol information from power supply and output the data control information to three output channels in PWM modulation mode.There are 24 data control bits in the transmission protocol,and each channel of the chip can realize the gray-scale modulation of 256 levels.6.The circuit functions of XD861 A and XD9860 are simulated based on MXIC 0.5 um CMOS technology.The simulation results meet the design requirements,and the layout of the two chips is designed and implemented.