The Design Of A White Backlight LED Driver For Protable Electronics

Requirements can promote the development of research. In particularly, the selling ofconsumer electronic products promotes the development of the power management unit. Asportable electronic products, one of the most important parts of power management unit, whiteLED backlight driver IC has made a great progress. Based on step-up (boost) DC-DC conversiontopology structure, I have designed a constant current driver chip with series load. Simulationresults show that the input voltage can vary from3.4to5.5V. It can also output20mA constantcurrent, drive up to6series white LED lights, and the conversion efficiency is over90%.Firstly, after a brief analysis of the three DC-DC conversion topology structures, I modeledvoltage-mode (VM) and current-mode (CM) structure of the driver chip, simulated and verifiedthe feasibility of the system. Secondly, in connection with the simulation results I analyzed andcompared the two structures. A detailed analysis on how to ensure the stability of the systemloop is carried out. Thirdly, in the subsequent part of the circuit design, it contains eight keymodules such as low voltage band gap reference, error amplifier, oscillator, peak currentdetection, slope compensation and so on. The band gap reference makes use of resistors toachieve low-voltage reference source. Stability of the system is taken into account in the erroramplifier design. The slope of the slope compensation module has a certain degree ofself-adaptive. In addition, the over-temperature protection and other peripheral modules aredesigned in order to ensure the reliability of the system. Fourthly, the overall simulation resultsof the chip based on the0.5μm CMOS process show that its maximum conversion efficiencyis92.39%, its start-up time is about1.5ms. However, the output voltage ripple is slightly large.In the end, in connection with the problems in the design， the advantages anddisadvantages of the chip, I proposed the direction for the solution, and the future developmentprospect of similar chips.