A High Level Of Integration Of Efficient Led Driver Chip

LED as a new generation of light, is increasingly attracting people’s attention, which advantage of its green energy saving and environmental protection will rapidly replace incandescent lamps and other lamps. Currently, LED in the application of display and backlight has already been mature, its driver chips are maturing,too. However, the field of LED lighting in China is still in the preliminary stage, LED lighting driver chips are common power management chip, dedicated LED lighting driver chip is still in blank. In this paper, a special LED lighting driver chip used in low-power LED lighting circuits is designed, which is hoped to break the foreign monopoly in this area of technology, reduce costs and get a wide range of applications.First, this paper introduced the current status and future trends of the development of LED driver chips, then it clarify the significance of this research. From the existing LED driver chips used in a variety of structures, the SEPIC topology is selected. In this paper, the working principle, advantages and disadvantages of SEPIC topology is analyzed, also, the entire of LED lighting circuits is designed. For completing a LED driver chip, it integrates the control of the driver circuits including gain modulation module, voltage and current transconductance error amplifier, bandgap reference, oscillator, over-voltage and over-current protection circuits, driver circuits and so on.In this paper, the design of LED driver chip has the function of power factor correction, meets the characteristics of the less pin count and low cost. In addition, the driver chip uses synchronous rectification technology, which can prevent the switches conducting at the same time through designing the appropriate dead time. This circuit system uses SEPIC topology, can directly use the AC power as input voltage and drive low-power LED lighting circuits.The expected design of LED lighting circuit was verified, debug the test board successfully and make the circuit work properly. The circuit modules and the entire chip were simulated on CSMC process, which can drive three1W led on typical, the output current was350mA, basically met the expected objectives and requirements.