Design Of Programmable DC Constant-current Source Based On ARM

With the development of modern electronic instruments, constant-current source, one ofthe key components of an electronic system, has received considerable attentions in thepast few years. Nowadays constant-current sources with high precision, high stability, lowripple, wide scale and high reliability are greatly desirable.In this thesis, a robust programmable constant-current source has been designed andimplemented. The proposed system consists of main control unit, linear regulator, D/Aconverter, constant-current output circuit and data sampling circuit.In the proposed constant-current source system, LPC1114has been adopted as themain control unit. The output value of current is automatically sent back to it andcompared with the input value, which is realized by feedback loop circuit. Based on the PIcontrol, the difference between these two values is less than a given tolerance. After theappropriate implementations of the proposed constant-current source system, itsperformance has been tested and analyzed systematically. Excellent results have beenachieved. It is shown that the designed system has the advantages such as wide scale ofoutput current (200mA and2000mA), low adjustable step size (2mA), high precision(absolute error less than0.1%+3mA), low ripple and high stability. It is thus expected thatthis system may have potential applications in many fields.