大电流高精度恒流源

为了满足在白光LED照明、蓄电池的快速充电器、电气触点微电阻测量、实验室等诸多领域对恒流源的需求,本文阐述了以单片机为控制核心,控制由运算放大器和复合型大功率晶体管构成的低成本恒流源系统的设计和制作.该系统由数控模块、恒流源模块、直流电源模块组成.通过键盘设定恒流源的给定电流值,经单片机运算处理后,由D/A输出高精度电压信号作为大电流线性恒流源的输入参考电压,达到数控恒流的目的.测试结果表明,本恒流源在20～2000 mA输出电流时,输出电流与给定值误差小于1 mA,纹波电流≤0.2 mA,控制精度较高,设计方法实用有效.

Design and implement of big-current, high-precision and invariable current source

To satisfy the demand of invariable current source in white light LED illumination,fast charger of accumulator,laboratory fields,we demonstrate the design and implement of low-cost invariable current source system controlled by SCM(Single Chip Micyoco)composed by operational amplifier and compound high-power transistors.This system is made up of the digital control module,the invariable current source module and the DC power supply module.Given current's value is set by keyboard,after processing in SCM,digital control invariable current can be achieved by providing the high-precision voltage signal output by D/A as the input reference voltage signal of the big-current linearity invariable current source.The test result illustrates that the error range of the output current value and the given value is less than 1mA and the ripple current is less than 0.2mA when providing the output current value is between 20mA to 2000mA,which indicates the high precision control and the applicable of this system.