毫安级可控恒流源设计

Milliamperes controllable constant current source design

在检测安全气囊的工作电阻时,为使得工作能够安全高效的进行,文章设计出了毫安级高精度可控恒流源。该恒流源由两大块组成,分别是恒流源控制模块和电源模块,文章中将镜像电源电路作为恒流源控制模块,采用精密电阻Ro作为采样电阻,把Ro输出的电压通过AD芯片反馈给控制系统,经过程序运算,控制DA芯片输出电流,把输出电流转变成电压,然后经过放大电路进行调整输入恒流源控制模块电压,从而实现恒流源可调。最后,通过实验验证,该直流恒流源电流最大误差为3.23%,满足5%以内的要求;最大纹波系数为0.00032%,满足低于0.001%的要求。

In the detection of the working resistance of the airbag, in order to make the work can be safe and efficient, in this paper, a high precision and controlled current source is designed. The constant current source consists of two parts, respectively is the constant current source control module and power module. In this paper, the mirror power circuit is used as a constant current source control module, the precision resistor Ro is used as the sampling resistance. The Ro output voltage through AD chip is feedback to the control system, and then through the output current operation program of the DA chip is controlled, and the output current is converted into a voltage, then after adjusting the input amplifier circuit of constant current source voltage control module, the constant current source can be adjusted. Finally, the experimental results show that the maximum error of the DC current source is 3.23%, which meets the requirement of 5%. The maximum ripple factor is 0.00032%, which meets the requirement of 0.001%.