一种基于单片机的数控直流恒流源的设计

Design of a Numerically controlled Constant-Current Source Based on Microcontroller

该数控直流恒流源采用模块化,通过开关和按钮的设置,配合INTEL AT89C55单片机的编程实现数字控制,数字显示,同时用DAC0832实现D/A转换,输出模拟控制电压,再用运放和功率三极管组成电流负反馈系统来完成输出电流控制及恒定。整个系统由单片机控制,输出部分使用运算放大器和功率放大器组成深度电流负反馈大大减少了输出端的电流波动,使系统输出电流误差<1 mA,纹波电流≤0.2mA。

The modular design of the numerically controlled constant-current source is adopted. Through the setting of switches and buttons, digital control and display are accomplished by INTEL AT89C55 microcontroller programming. The DAC0832 is used to implement D/A converter and output the analog control voltage. Further, current negative feedback system constructed by operational amplifier and power transistor is realized to achieve output current control and constant. The whole system is controlled by the microcontroller and its output unit can greatly reduce the fluctuation of output current with output current error 〈 lmA and ripple current 〈 0.2mA.