System Design of Digitally controlled Constant Current Source

摘要

In order to provide stable and adjustable current source for portable systems,this paper designs a digitally controlled constant current source.According to the input of independent key,the output of the microcontroller digital volume controls digital-to-analog converter by Voltage-Current conversion module to get the constant current output.The output module consists of the operational amplifier and the power transistor TIP 122,which is used for voltage-current conversion.At the same time,the value of output current is obtained by sampling resistor to convert the real-time acquisition and monitor the output of constant current source.The experimental results show that the system output ranges from 0 mA to 240 mA.The value of constant current can be controlled by stepper key,and the measurement error ratio can meet the requirement of design.