Design and realization of a new type of constant current source with small current and high precision

Using constant current source as the excitation signal is an effective method for system testing of the aircraft. At present, the constant current source circuit built by TL431 voltage regulator does not meet the system test requirements of the aircraft under the condition of small current output. And when the temperature span is large, the working circuit does not have the ability to inhibit the temperature drift, of which the temperature drift is large. In this paper, the constant current source circuit built by TL431 voltage regulator is improved. Adding OP77 and π-type filter circuit to ensure the output accuracy, the design ofthe resistor network can achieve complementary temperature coefficient. Temperature drift is reduced by adjusting the appropriate compensation point. Finally, the superior performance of the improved constant current source is verified by simulation and experiment.