MAX31865 Temperature Sensor Module

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 0°C, 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. A 430Ω 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 for For Arduino or microcontroller.

NOTE: RTD sensor is not included!

Specifications:

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

1. Simple Conversion of Platinum RTD Resistance to Digital Value
2. Handles 100Ω to 1kΩ (at 0°C) Platinum RTDs (PT100 to PT1000)
3. Compatible with 2-, 3-, and 4-Wire Sensor Connections
4. SPI-Compatible Interface
5. 20-Pin TQFN and SSOP Packages

● High Accuracy Facilitates Meeting Error Budgets

1. 15-Bit ADC Resolution; Nominal Temperature Resolution 0.03125NC (Varies Due to RTD Nonlinearity)
2. Total Accuracy Over All Operating Conditions: 0.5NC (0.05% of Full Scale) max
3. Fully Differential VREF Inputs
4. 21ms (max) Conversion Time

● Integrated Fault Detection Increases System Reliability

1. ±45V Input Protection
2. Fault Detection (Open RTD Element, RTD Shorted to Out-of-Range Voltage, or Short Across RTD Element)