| Since the energy is consumed constantly behind the economic development, people are looking for new energy. At the same time, people improve the energy usage efficiency with the development of science and technology. The LED in lighting industry is an outstanding representative. The LED has improved significantly on the illumination and the work efficiency compare to the old incandescent lamp. LED can match more intelligent drive circuit as a newly lighting device to adapt more lighting conditions. The continuous improving performance of LED drive circuit is something every designer who works with LED industry should think and improve. Higher light efficiency is also the goal designer constant pursues. Due to its own single stage conversion luminescence properties, LED has a high energy efficiency compares to ordinary car headlight’s two stage conversion luminescence properties. LED’s working life can reach 100000 hours under the normal operating condition. It gets the favors of all the auto makers because of its ultra-long working life and the characteristics of energy conservation and environmental protection. With the development of automotive electronics market, LED grows rapidly and then it is necessary that designing different LED drivers to meet different automotive environments. Then a micro-level heat LED photoelectric three aspects of performance analysis, as well as the LED driver design fully prepared.In the three micro-aspect which include thermotics,optics and electric to analysis LED, design the driver of car LED combined with the application environment of car.LED current requires a stable, linear, adjustable, reliable performance. Secondly,LED driver topology such as BUCK, BOOST topology specific analysis, followed by a variety of mechanisms to protect the LED driver for effective analysis and sequential analysis of its importance for the various modules of the chip design trade-offs when laying the groundwork, including thermal protection, over-current protection, short circuit protection, dimming modes for a variety of analysis shows the advantages and disadvantages compared to each other at the same time, anticipate potential problems.Based on the above analysis, we use of 0.8um BCD technology to design a LED driver chip of the car with a wide input voltage and high current and adjustable output current and over-temperature protection and open-circuit protection. The generalframework of chip design which includes power modules, voltage reference module,current reference module, over-temperature protection module, PWM dimming module and open-circuit protection module. Some modules of the design in the design process by comparing the optimum design trade-offs to complete the entirely chip design.Eventually I have introduce some chip packages to make the design integrity of the entire chip to be resolved.I have achieve the desired design goals by the simulate of all parts module and in accordance with the results obtained confirm the functional data. |
