| Switching Mode Power Supply (SMPS) is a high efficiency power supply by controlling the open and off time accurately. As the battery life required by customer portable electronics grew higher and higher, the market of switching power supplies is getting bigger. Our design: Current Model DC-DC Buck Converter mainly aims at this market requirement.The design job begins with chip diagram extraction and reorganization. We improve the performance of the reference chip by adding the PFM/PWM selector, PFM driving function and optimizing some blocks. We have analyzed the system stability with Matlab. With a detailed bocks and system simulation, we could promise a correct circuit. After that, we have laid the whole chip. And then, we have submitted the GDSII file to the foundry. At last, we have done some primary testing with the sample chips.This paper analyzed the relative system knowledge of DC-DC power supply, the advantage and disadvantage of different system topologies, and also the detail information of the main blocks in this design with the simulation and testing results. We have also introduced the key problems when you layout .And the whole chip layout diagram has been given. At the last part of this paper, we have talk about the testing data comparing with the simulation data. Finally, a conclusion has been given.Our design have used the CSMC 0.5μm DPTM process for cost saving. A PWM/PFM hybrid control structure has been implemented for gaining a high efficiency at a wide load range. Our chip could work well at 1.6-5.5v input voltage. The last load current is about 400mA. The working frequency is 1.5MHz. The efficiency is 75% and above at PFM model, 80% and above at PWM model.From the testing result, this chip has realized the basic functions. But, there are also some flaws. The testing results are somewhat different from the simulation results. In this paper, we analysis the main result that cause these difference, and also some improvement method has given. |
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