| With the rapid development of electronic technology and information technology, the portable electronic device is widely used. Highly integrated and low consumption switching powers are increasingly demanding. Therefore, integrate-able switching power converter control is becoming focus of the study.First this paper introduces the DC/DC voltage converter working principle and provides a detailed analysis of the topology of the voltage step-up or step-down converter. The advantages of the PWM peak current mode control and synchronous rectification are also introduced. Then the system stability is analyzed in detail, and proposing methods for system frequency slope compensation and system frequency compensation.From the switching power supply applications needs in the market demand for highly integrated way, through system design, circuit design and back-end layout sdrawn, designed a boost and buck integrated voltage converter.The integrated voltage converter’s working mode can be determined by external selection port:if the port input level is high, the converter is a boost mode; selecting port input level is low, the converter is a buck mode. System uses peak current mode PWM control mode which can provide fast transient response and excellent loop stability. Synchronous rectification can improve the conversion efficiency of the system.This work designed an integrated Buck and Boost voltage converter based on SMIC0.35μm CMOS2P2M process. Using spectre for each sub-circuit simulation, and finally complete the overall layout drawing of the circuit. The converter has a voltage range of2.7V-5.5V for both input and output;the maximum protection current is2A and a fixed frequency of1MHz. The maximum conversion efficiency up to94%. The converter also has overcurrent protection, thermal protection, overvoltage protection. Chip indicators meet the design requirements, can be widely used in digital cameras, digital cameras and laptop computers and other portable devices. |
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