Design And Test Of A High Power LED Driver Chip

LED is becoming one of the most promising high-tech energy-saving industries and gradually replacing the traditional light source because of its small size, low power consumption, long life, low heat, environmental protection, etc. Especially successful development of the high power white LED, accelerates the whole lighting industry upgrading, also make the design research of white high power LED driver more realistic.This paper designs a single channel high power LED driver chip. This chip adopts the peak current PWM control mode, and uses a dynamic slope compensation circuit to eliminate harmonic oscillation problem, the chip can change switching frequency,the maximum switching frequency is 1.34M. In addition, the chip has some functions of soft start, voltage protection, over-voltage protection and open-protection.This paper first studies LED light principle and characteristics, analyses the connection mode and driver types. The DC-DC switch power supply of the basic principles, including four basic topology structures, modulation mode and feedback control method are also studied. Then, this paper gives the design of the chip performance characteristics, system structure, the function of each module is introduced and the main device the parameter selection. This paper designs a dynamic slope compensation circuit to eliminate harmonic oscillation problem. Also this paper analyzes the power consumption of the chip, and analyses the switch tube conduction loss, switch loss, gate drive loss and rectifier diode losses in detail, and gives corresponding optimization scheme. In addition, this paper analyses some modules of the chip, including band-gap, error amplifiers, oscillator, frequency conversion circuit, and gives corresponding simulation results. At last, the simulation and test results of the whole system is given.The chip is based on HHNEC BCD350 process.The simulation results show when the input voltage is 8V, the maximal output voltage is 38.81v, the maximal output current is 977mA.The test results show when the input voltage is 8V, the maximal frequency is 1.3M, the maximal output voltage is 38.06V.