Abstract:Aiming at the requirement of DC power supply for automatic detection and other application systems, a digital adjustable power supply system is designed. The digital adjustable power supply system selects the single chip microcomputer (AT89S51) as the core control component. The peripheral module circuit includes the AD conversion module composed of MCP4921, the voltage and current amplification module and the sampling voltage step-down module based on the integrated operational amplifier LM324, and the LCD display. Module and power supply module based on 78 series, 79 series integrated voltage regulator chip design. The system software design uses C language to design the modular program structure. The test of results show that the adjustable DC voltage range of the system is 0V-12V, the output DC current is 500mA, the voltage error is less than 0.1V, and the target voltage can be set through the keyboard circuit. It has the characteristics of simple design, stable output voltage and reliable performance.