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针对DC-DC转换系统恒流、恒压及不同限流值的需求,提出了一种外部可调限流型恒流/恒压DC-DC转换系统的设计方案.该方案由外部可调限流电路、电流误差放大电路、电压误差放大电路、锯齿波产生电路、斜坡电流采样电路和逻辑驱动电路构成.系统的输出电流和输出电压确定了一个临界负载电阻值,当输出负载小于此临界值时,系统工作在恒流模式;当输出负载大于此临界值时,系统工作在恒压模式.基于UMC 0.35μm CDMOS工艺,通过输出恒流为1A、恒压为3.3V及外部可调电阻范围在20～120 kΩ的具体实验,验证了该系统的恒流/恒压及外部可调限流功能.,In order to meet the different needs of DC-DC(direct current to direct current) converter system in CC (constant current),CV (constant voltage) and current limiting,a design scheme of periphery adjustable current limiting type CC/CV DC-DC converter system was proposed.The system consisted of periphery adjustable current limiting circuit,current error amplification circuit,voltage error amplification circuit,saw-tooth generating circuit,ramp current sampling circuit and logic drive circuit.The critical load resistance value depended on the system’s output current and output voltage.When the output load was less than the critical value,the system operated in constant current mode,otherwise the system operated in constant voltage mode when the output load was greater than the critical value.By actual experiments,such as CC of 1 A,CV of 3.3 V and the extal adjustable resistance from 20 kΩ to 120 kΩ with UMC 0.35 μm CDMOS process,the functions of CC,CV and periphery adjustable current limiting for the system were verified.