Adafruit PT100 RTD Temperature Sensor Amplifier - MAX31865

The Adafruit PT100 RTD Temperature Sensor Amplifier is a breakout board for the MAX31865 precision RTD-to-digital converter. It reads 2-, 3-, or 4-wire PT100 platinum resistance temperature detectors over SPI, delivering laboratory-grade temperature accuracy and repeatability that surpasses thermocouples.

PT100 RTDs use a platinum resistor element (100Ω at 0°C) whose resistance changes predictably with temperature. The MAX31865 handles signal amplification, wire compensation, and analogue-to-digital conversion — you simply read the resistance ratio over SPI and convert to temperature. The board includes a 430Ω 0.1% precision reference resistor and is 5V-safe with an on-board 3.3V regulator and level shifting.

Key Features

• MAX31865 RTD Amplifier – Precision ADC with automatic wire resistance compensation
• 2-, 3-, or 4-Wire RTD Support – Compatible with any PT100 (100Ω at 0°C) sensor
• 430Ω 0.1% Reference Resistor – Pre-installed for PT100 sensors
• SPI Interface – Works with any microcontroller; example code provided for temperature calculation
• 5V Safe – On-board 3.3V regulator and level shifting for use with Arduino and other 5V boards
• Screw Terminal Blocks – Two 2-pin terminals for connecting RTD sensor wires

PT100 vs PT1000

This board is configured for PT100 RTDs (100Ω at 0°C). If you have a PT1000 RTD (1,000Ω at 0°C), a different version with the appropriate reference resistor is available.

Ideal For

• Precision temperature measurement in laboratory settings
• Industrial process monitoring and control
• Food and beverage temperature logging
• Scientific instruments requiring high accuracy and repeatability

Package Contents

• 1× Adafruit MAX31865 RTD Amplifier Breakout (assembled)
• 2× 2-pin screw terminal blocks (colour may vary)
• 1× Header strip (requires soldering for breadboard use)