| In recent years, as the rapid development of LED lights, all kinds of LED light have constantly emerged, especially the high brightness LED lights, which has got very wide attentions. From the LED lamps, wall lamps, spotlights, lamps and other LED products, the rapid development of LED market can be seen, and this development is also expected to continue for some time in the future. Therefore, the LED power converter chip that is the support circuit of high-brightness LED lamp, which is also known as the driver IC circuits, and it has become a hot topic in this industry.In this paper, aiming at the characteristics of the high power LED driver circuit, a LED lighting driver circuit that has high precision and efficiency is proposed and designed. The accuracy error of output drive current is within one percent, and the conversion efficiency of the overall circuit is up to ninety-six percents or more, and the output drive current is 350mA. It can drive up eight HB LED lights of 1W. This design is based on CSMC 0.5μm40V BCD handicraft, and the layout area is about 1.4mm×1.4mm. This paper verifies the feasibility of this design. Some innovations on the basis of the traditional driver circuit are the biggest highlights of this article, the main contents and results including:1. In the architecture of the driver chip, the average current control mode is adopted to replace the traditional peak current control mode. It can not only control the output current of LED driver accurately, but also improve the accuracy of the output current, that is the ripple is within one percent, and it improves the stability of the circuit further.2. In the structure of the driving circuit, a detailed comparative analysis is conducted on the power switching tube when it is used in the converter, and then the study and discussion based on the current of various feedback circuit is combined. So the BUCK topology structure that is low-level and low-side is selected as the topology structure of the final drive circuit.3. In the internal circuit of the IC chip, the over temperature protection circuit is essential for the high-power LED driver circuit. By converting the circuit masterly, it can make the deviation that is brought in the technology production process by the resistance ignored, so it improves the accuracy of the over temperature protection circuit greatly and protects the driver chip very well. The reference voltage circuit with curvature compensation is similar to the over temperature protection circuit. It makes use of the characteristics of the transistor in the technology, through a transistor to achieve curvature compensation.4. The circuit designs of other modules, includes the core error amplifier circuit. The small signal circuit of it is analyzed completely and its transfer function is studied to obtain the frequency characteristics accurately. The oscillator circuit is also essential, which uses the bias circuit to adjust the frequency. That also contain the designs of the built-in voltage regulator circuit, the PWM circuit and so on.5. Based on CSMC 0.5μm40V BCD handicraft, the circuit characteristics of the simulation module and the features of the LED driver circuit, it can basically meet the desired goals. |
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