Research on Thermistor Simulation Based on Digital Potentiometer for Microsatellites

The simulation of thermistors plays an important role in micro satellite thermal control subsystem test. The simulation generally adopts the programmable resistors. However, the traditional programmable resistor module designed with relay switching precision resistor technology has its disadvantages, e.g. Low integration and short lifespan. To overcome these shortcomings, the thermistors simulation module based on digital potentiometer is designed and developed. The design adopts digital potentiometers as the core chips, a big resistance digital potentiometer and a small resistance digital potentiometer are connected to form the programmable resistors channel. DSP is used as the main controller in this design, it communicates with computer via RS-485 bus. Since digital potentiometers have big inherent error, the control values of digital potentiometers are calibrated. 32-channel programmable resistors ranging from 2kΩ to 200kΩ are integrated on a 160mm×100mm board. Due to the application of the digital potentiometers, the integration and lifespan of the module are greatly improved compared to traditional modules. The module has been applied in the test of micro satellites thermal control subsystem, the test results show that the module can meet the technical specifications.