Design Of A Boost DC-DC Constant-Current LED Driver IC

As the fourth-generation lighting source,LED has become the new favorite of lighting technology with many excellent features.It has been widely used in various lighting fields,and gradually replaces various traditional lighting sources.LED drivers provide stable voltage or current for LEDs,which is an indispensable part of LED products.In order to meet the driving requirements of LEDs,researchers have developed various drivers and continuously improve their operating performances.Paying more attention to the research and development of LED drivers is the national demand of China's chip independence and the key to the development of China's LED industry.Based on a large amount of literature research,this thesis summarizes the development history and research status of LEDs and the LED drivers.The basic principles related to LED driving are systematically introduced to provide reference for later researchers.Focusing on low-voltage LED display applications,this thesis proposes a practical LED driver integrated circuit.The chip combines dual-current-loop control technology and PWM modulation technology to provide a constant drive current for the LEDs.At the same time,the chip has multiple protection mechanisms,such as undervoltage protection,overvoltage protection and overtemperature protection,which results in considerable reliability.This chip can be used with a low-voltage DC power supply of 2.6V~5.5V,and its operating temperature ranges from-25? to +85?.The 2 to 8 white LEDs in series operate steadily by employing this chip in a boost topology circuit.The thesis presents the system design plan of the chip,and provides the detailed design analysis to some function modules.During the design process,an improved RC oscillator structure,an improved bandgap reference(BGR)and an undervoltage protection circuit with a built-in BGR are proposed,in consideration of the chip's workflow and design requirements.After completion of the circuit design,under a 0.25?m BCD process,the designed chip has been fully simulated and verified by Cadence software,and the layout design of the chip was completed.