Design and realization of the intelligent temperature transmitter

The analog input signals of intelligent temperature transmitter (ITT) are milli-voltage signals, AD7714 was selected was selected for small signal acquisition. The new technology of potential lifting was explored to ensure the stability and accuracy of sampling. The wiring technology of small signal was presented. ITT´s switching power supply was designed to meet the requirements of security and isolation. The parameter calculation of high-frequency transformer was mainly researched. Constant current source circuit was designed to measure the voltage of resistance temperature detector (RTD). The method of transforming dividing table into flash memory was also presented. ITT can be connected with multi-type RTD, multi-type thermocouple and millivolt signal. The test error is about ±1°C in -200°C~850°C when Pt100 is used.