Design Of Constant Current Driver Chip For LED Display

Light Emitting Diode(LED)is a kind of new high efficient solid light source in common use.It has the advantages of energy saving,low power consumption,green environmental protection,long service life and so on.It meets the needs of market application and social development.With the continuous improvement of LED luminous efficiency and the decrease of cost,the LED display screen,as an important application of LED,continues to expand the market scale and has a promising market prospect.LED display is widely used in all walks of life,the constant current driver chip of LED display plays an important role.The continuous optimization of the LED display driver chip makes the images and videos displayed by the LED display more clear and delicate,and the colors more natural and real.This design is based on the analysis of the overall structure principle of the LED display driver chip.According to the specific performance requirements,it focuses on the in-depth analysis of the basic principles of the main sub-circuits of the analog circuit,and completes the circuit design and simulation verification.Ways in this paper,design of LED display dimming in analog circuit part through the linear change of output current dimmer,the built-in scattered adjusting mode pulse width modulation(SPWM)can increase the refresh rate and chip gray modulation ability,improve the quality of images showed.SPWM is a kind of important way of LED display light regulating mode,produced by the digital module is used to control the output channel current.The digital part of this paper will focus on SPWM control mode in the working principle of LED display gray data processing.The whole analog circuit is added with SPWM regulation mode to carry out simulation verification of the simulation module.Finally,the main points of the design of the layout and wiring of the chip layout are introduced.The test results show that each module meets the requirements of the design index and the chip can realize the function well.In this paper,a 16-channel LED display constant-current driver chip is analyzed,designed and streamed.Using 0.18?m BICMOS process,the power supply voltage range is 3.3V?6V,each channel output current range is 0.5m A?30m A,the channel output current size is adjustable.In this paper,the maximum operating frequency of the constant-current driver chip is 35 MHz,and the maximum error of the output current between channels is no more than ±1.5%,and the error of the output current between chips is less than ±1.5%.The high precision of the output current of the chip designed in this paper is conducive to improving the display effect of the LED display screen.