Design Of12bits Double-input Single RGB Driver

With the advantages of small size, long service life, high luminous efficiency,and low-power consumption, LED is becoming the new generation of light source ofthe world. In the current society, energy saving and low-carbon are promoted, LEDtechnology is developing rapidly, the demand for a large number of driver chips, andthe majority need to use foreign products, to design a high performance LED driver isnot only has a huge market demand and generate substantial economic benefits, alsohas great significance for the development of China’s LED display technology.The paper designed a two-wire input single-channel RGB output LED constantcurrent control chip. Use Spectre for the schematic design and simulation，useVirtouso for layout design, use Calibre for the DRC and LVS. The supply voltageranges from3V to5.5V, using0.5um CMOS process, the chip has R, G, B threeoutput channels, the channels and current matche precisely. The advantages of thischip is small size, flexible application, and simple circuits, convenient adjustment ofthe output current and lower cost. It can be applied to LED display devices like pixelpoint light source, decorative LED light source.The chip has high precision current matching and can used in tandem, Comparedwith similar products,the chip has three advantages:first,12bits PWM grayscale adjustment accuracy, the majority of productscurrently on the market have8bits grayscale regulation accuracy. The driver chipdesigned in this paper has grayscale adjustment accuracy of12bits, which meanseach output can achieve4096gray-scale changes, it also can provide more richercolor with the combination of RGB.Second, it can control output current by five bits data,15bits programming datago through three channels of the input,which makes the output current range from2mA to36mA, and eliminate the palaver of changing the resistance is to set thechannel current.Third, the I2C-compatible input, data and clock two-wires input, do not need the port of latch, which makes a low complexity of the chip pins and makes theexternal circuit more easy, it also very convenient to multiple series connection andintegration.The design of this LED control chip is done with the standard forward designsteps strictly, in the beginning, do the pre-product market research to determine thefunctionality and performance of the chip, look up a lot of documents at home andabroad, make sure the function of internal sub-modules, then design and simulate thesub-modules, the next do functionality and performance simulation and layout of thechip, parasitic extraction and post-simulation, Tape-out chip.