Platinum (PT100) RTD Temperature Sensor Amplifier – MAX31865

The MAX31865 is an easy-to-use resistance-to-digital converter optimized for platinum resistance temperature detectors (RTDs). An external resistor sets the sensitivity for the RTD being used and a precision delta-sigma ADC converts the ratio of the RTD resistance to the reference resistance into digital form. The MAX31865’s inputs are protected against overvoltage faults as large as 45V.

For precision temperature sensing, nothing beats a Platinum RTD. Resistance temperature detectors (RTDs) are temperature sensors that contain a resistor that changes resistance value as its temperature changes, basically a kind of thermistor. In this sensor, the resistor is actually a small strip of Platinum with a resistance of 100 ohms at 0C, thus the name PT100

The MAX31865 handles all of your RTD needs, and can even compensate 3 or 4 wire RTDs for better accuracy. Connect to it with any microcontroller over SPI and read out the resistance ratio from the internal ADC. A430 0.1% resistor as a reference resistor on the breakout is used.

We even made the breakout 5V compliant, with a 3.3V regulator and level shifting, so you can use it with any forFor Arduino or microcontroller.

NOTE: RTD sensor is optional!

Integration Lowers System Cost, Simplifies Design Efforts, and Reduces Design Cycle Time

• Simple Conversion of Platinum RTD Resistance to Digital Value
• Handles 100 to 1k (at 0C) Platinum RTDs (PT100 to PT1000)
• Compatible with 2-, 3-, and 4-Wire Sensor Connections
• SPI-Compatible Interface
• 20-Pin TQFN and SSOP Packages

High Accuracy Facilitates Meeting Error Budgets

• 15-Bit ADC Resolution; Nominal Temperature Resolution 0.03125NC (Varies Due to RTD Nonlinearity)
• Total Accuracy Over All Operating Conditions: 0.5NC (0.05% of Full Scale) max
• Fully Differential VREF Inputs
• 21ms (max) Conversion Time

Integrated Fault Detection Increases System Reliability

• 45V Input Protection
• Fault Detection (Open RTD Element, RTD Shorted to Out-of-Range Voltage, or Short Across RTD Element)

Specifications

Resources

Datasheet
Libraries
Sample Code

Tutorials