| With the rapid development of electronic information technology in recent years,more and more portable electronic products have entered people's lives.Since portable products are powered by batteries and battery capacity is limited,the market places higher demands on the efficiency of power chips.Switching power supply has gradually replaced traditional linear power supply due to its high efficiency and small size.DC-DC power supplies are widely used due to their flexible voltage conversion methods.However,the output voltage of the DC-DC power supply contains ripple voltage,which is disadvantageous for circuit modules powered by DC-DC.Based on the market demand for high efficiency and low ripple,this paper designs a high efficiency,low ripple Buck DC-DC converter.The main research results are as follows.1.Based on the analysis of various basic control methods and modulation methods,a peak current mode PWM control method is used to design a Buck DC-DC converter with a wide input voltage range(4.5V~40V)and an output current of 1A.The output voltage can be adjusted by an external feedback resistor(0.8V~15V).Peak current mode control allows the system to have faster load response speeds and simple loop compensation.2.Based on a detailed analysis of the bandgap reference operation principle,in order to achieve high efficiency,a low-power bandgap reference architecture is adopted to reduce the quiescent current to only 14.5?A while ensuring certain performance.The static power consumption of the module is reduced,which is beneficial to improve the overall conversion efficiency.3.Several common current sampling structures are analyzed and compared,and the structure with lower power consumption is selected as the design basis of this paper.At the same time,the structure of the slope compensation is simplified and combined with the current sampling module,which greatly reduces the complexity of the circuit and the consumption of quiescent current.4.The traditional high-voltage levelshift structure is analyzed in detail,and the shortcomings of slow conversion speed and large power consumption are targeted.The simulation results show that the conversion speed of the improved high-voltage levelshift module is increased by about 4 times,the dynamic power consumption is reduced,and the system conversion efficiency is improved.5.Based on the 0.5?m 40 V BCD process,the sub-module and the whole circuit are simulated and verified by software such as Cadence and Hspice.The simulation results show that all the indicators have reached the design goal. |
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