Research And Design Of A Buck Converter Based On Adaptive Constant Conduction Time

With the rapid development of electronic technology，intelligent mobile phones,notebook computers, tablet PC, and other electronic products gradually into the generalpopulation, and become the people daily life necessities. Power supply as the heart ofthe electronic products, electronic products directly determine endurance and life. Inorder to improve the performance of the electronic products, the solution of the powerproblem is the key. Currently, the power source development is divided into linearpower supplies and switching power supply. Linear power supply due to low efficiencywas gradually replaced by switching power supply. Switching power supply with lowconsumption, high conversion efficiency, low cost etc, and have been widely used in theelectronic world.DC/DC converter as an important part in the field of switch power supply, cancarry on the flexible transformation to the dc voltage. So, it can realize buck, boost,buck-boost and polarity inversion functions. Therefore, DC/DC converter much thefavour of people, is widely used in smart phones, digital camera, tablet PC, MP3/4, andother electronic products.A synchronous rectification Buck DC/DC converter chip which adopts adaptiveconstant conduction time modulation method (ACOT) is present in this thesis. The chiphas wide range of input voltage (4.2V~16V), output voltage can be adjusted (0.8V~13V), the highest output current can reach to3A.Using the synchronous rectifiertechnology, make heavy conversion efficiency as high as97%, at the same time as aresult of the ACOT control mode, in the light load situations converter minimumconversion efficiency as high as83%.The chip Integrated thermal protection, overcurrent protection, over current protection, ESD protection. The chip can provide goodpower solutions for communication equipment tablet PC, laptop computers, LED driver,etc.This thesis first introduces the development trend of switch power supply, and thenanalyses several kinds of switch power control mode and its principle, and on this basis,this paper discussed the design of the function of the chip characteristics, system architecture and peripheral application design.This thesis completed the loop control related sub_module circuit design, including:LDO voltage regulator circuit, bootstrap circuit, On_Timer timer circuit, power tubegate drive circuit, slope compensation circuit analysis and design. And use Cadence andH_spice, in0.6μm CD (CMOS and DMOS) technology, to simulate and verify thecorresponding circuit, if satisfy the corresponding indicators. The whole circuit will besimulated. The simulation results show that the system has good dynamic characteristicsand higher efficiency. Finally, according to the selected process conditions, the chipcompletes the end design.