一种实用的毫安电流信号输出电路

摘要

在工业控制中,采用传统的D/A转换电路将数字信号转换成毫安电流时存在数据路线多、结构复杂的问题.对此,设计了一种实用的变换电路.该电路通过滤波和电压电流变换,将脉宽调制PWM信号转换为4～20 mA的电流信号,并通过改变PWM信号的占空比简单精确地控制输出电流大小.试验结果表明,该电路线性度好、精度高,适用于前级为可输出PWM信号的微处理器.%In industrial control, the traditional D/A conversion circuit that converts digital signal into milliampere current is facing problems of many data lines and complicated structure, thus a practical conversion circuit has been designed. Through filtering and voltage to current conversion, this circuit converts PWM signal into 4 ～ 20mA signal, and the output current can be controlled through adjusting duty cycle of the PWM signal. The experimental research indicates that the circuit offers good linearity, high accuracy and suitable for the microprocessor which front stage may output PWM signal.