Design of Wide-Range High-Precision Constant Current Source Based on Microcontroller

A high-precision digital DC current source with the AT89S52 single-chip microcomputer as its core, is composed of a control circuit, digital-to-analog (D/A) conversion, display, analog-to-digital (A/D) conversion and other circuits. The D/A converter DAC0832 is used to control the output current of the voltage controlled constant current source, while the A/D converter ADC0804 is used to measure and provide real-time feedback on the output current. Through a program algorithm, the output current is continuously adjusted to approach the required current value. An independent keyboard is employed as the current output setting device, operating in the step-by-step mode, and the LCD1602 displays both the set current and the actual output current. Experimental results indicate that the output current of the constant current source can be set arbitrarily within the range of 10mA~ 2000mA. The system exhibits low ripple current, high measurement accuracy, and constant current stability under variable loads, all achieving an accuracy of 0.1%. Additionally, the step-by-step adjustment function of ±1 mA can be implemented through the keyboard.