MAX31856 Thermocouple Module – High Precision Development Board with Universal AD Converter

Description

The MAX31856 Thermocouple Module is a high-precision thermocouple-to-digital converter breakout board built around the Analog Devices MAX31856 IC. Unlike simpler thermocouple modules that support only one thermocouple type, the MAX31856 provides automatic linearization correction for eight thermocouple types—K, J, N, R, S, T, E, and B—making it a truly universal solution for high-temperature measurement .

The converter performs cold-junction compensation, signal amplification, and 19-bit digitization internally, outputting temperature data in Celsius over a 4-wire SPI interface. The thermocouple temperature resolution is 0.0078125°C, with thermocouple voltage measurement accuracy of ±0.15% (max, -20°C to +85°C) and cold-junction compensation accuracy of ±0.7°C . The device supports readings as high as +1800°C and as low as -210°C, depending on the thermocouple type .

Breakout modules typically add a 3.3V regulator and level-shifting circuitry, making the board compatible with both 3.3V and 5V microcontrollers . A screw terminal block accepts the thermocouple wires, and the board includes inline resistors and a filter capacitor for improved stability, as recommended by the manufacturer .

Critical limitations: The MAX31856 is a converter board, not a complete sensor—the thermocouple itself is a separate component. Many modules do not include a probe; verify with your supplier. The board requires 4 digital I/O pins for SPI communication. The high resolution (0.0078125°C) far exceeds the accuracy of typical thermocouples (often ±2°C to ±6°C), so the resolution should not be mistaken for accuracy .

Features

• Universal Thermocouple Support: Works with K, J, N, R, S, T, E, and B types—no need for multiple modules for different probes .

• Automatic Linearization Correction: Internal lookup table (LUT) corrects thermocouple nonlinearity for all eight types .

• 19-Bit, 0.0078125°C Resolution: Extremely fine temperature discrimination .

• Integrated Cold-Junction Compensation: ±0.7°C accuracy eliminates external reference components .

• ±45V Input Protection: Robust protection against overvoltage conditions on thermocouple inputs .

• Fault Detection: Detects open thermocouples, over/under temperature conditions, and over/under voltage .

• 50Hz/60Hz Noise Rejection Filtering: Selectable mains frequency filtering for cleaner readings .

• 3.3V/5V Logic Compatibility: Onboard regulator and level shifting simplify Arduino integration .

Technical Specifications