Design Of A High-Voltage And On-Chip Compensated BOOST White LED Driver

Along with the development of semiconductor materials, white LED has been ubiquitously used as small LCD backlignts in portable applications such as mobile phones and digit cameras for its high efficiency, high brightness and long life-time. White LED driver, as the critical part of the backlighting system, should be elaborately designed, for the tendency of miniaturization for portable devices requires high efficiency, high reliability of the White LED driver.With a deep study of current technique for White LED driver, three main driving methods surveyed at the beginning of this thesis. According to the specifications of the project, the structure of a Boost DC-DC driving technique is employed. Then, Peak Current Mode with PWM modulation is selected for the system. And based on a detailed analysis of the system stability issue and the conventional Type2compensation, an on-chip current-mode miller multiplier Type2compensator is designed to save chip area and fabrication cost. Important blocks are analysed and their simulation results are given in the next place. In addition, a dynamic slope compensation is applied in the system so that the open-loop instability during large duty cycles and over compensation are eliminated. The reliability of the system is further enhanced by the additional functions such as Under-Voltage Lockout, Over Current Protection, Over Voltage Protection, Over Temperature Protection, Soft Start and so on.This thesis presents an on-chip compensated high voltage Boost WLED driver chip using CSMC0.15μm BCD process. Schematic design, layout design, simulations and verifications of the system have been accomplished using EDA tools of Cadence. The input voltage range is from2.5V to5.5V, the highest output voltage is35V, the highest system efficiency is over90%. The simulation results are in consistency with design specifications.