Resistive Temperature Detector (RTD)
What is a Resistive Temperature Detector (RTD)?
Resistive Temperature Detectors (RTDs) are extremely accurate temperature sensors. They have consistent, repeatable performance and low drift error (-200°C to +850°C). RTDs provide the designer with an absolute result that is fairly linear over temperature. RTDs' linear relationship between resistance and temperature simplifies the implementation of signal conditioning circuitry. For high-precision applications, these sensors require a linearization look-up table in the microcontroller due to sensor nonlinearities.
Resistive Temperature Measurement Circuits
Circuit A can be easily modified for a desired temperature-to-frequency range. It uses the MCP6541 comparator and can be implemented with either precision, low-drift components, or a calibration step to achieve high accuracy. Circuit B utilizes pull-up and pull-down resistors to excite the RTD, employing the TC913A Auto Zero op-amp to amplify the small voltage changes that correspond to temperature.
