Thermocouple Amplifier MAX31855 breakout board (MAX6675 upgrade)

This Adafruit MAX31855K thermocouple breakout adds cold-junction compensation and easy digital interfacing for K-type thermocouples, with onboard 3.3V regulation, level shifting, and included terminal block + headers. Replaces the discontinued MAX6675, but isn’t pin or code compatible.

Thermocouples are extremely sensitive, so they need a proper amplifier with cold-junction compensation to give accurate readings. The Adafruit MAX31855K handles all of this for you, and it’s easy to connect to almost any microcontroller — even if your board doesn’t have an analogue input.

This breakout includes the MAX31855K chip, along with a built-in 3.3V regulator, 10µF bypass capacitors, and level shifting circuitry, all assembled and tested. It also comes with a 2-pin terminal block for connecting your thermocouple, plus a pin header so you can plug it straight into a breadboard or perfboard. It pairs perfectly with a 1m K-type thermocouple.

If you need support for other thermocouple types, there’s also a Universal MAX31856 amplifier board, which can be configured in the Arduino sketch to work with a wide range of thermocouples.

New: this version now uses the MAX31855K instead of the MAX6675, allowing a wider temperature measurement range. Please note that the MAX31855 is not pin-compatible or drop-in code compatible with the MAX6675. Adafruit provides Arduino libraries for both, but if you’re upgrading an older MAX6675 project, you’ll need to adjust your design and code. The MAX6675 has been discontinued by Maxim.

Features

• Works with any K type thermocouple
• Will not work with any other kind of thermocouple other than K type
• -200°C to +1350°C output in 0.25 degree increments - note that K thermocouples have about ±2°C to ±6°C accuracy
• Internal temperature reading
• 3.3 to 5v power supply and logic level compliant!
• SPI data output requires any 3 digital I/O pins.

Revision History

• As of June 6, 2024 – We added a pre-soldered terminal block and updated this PCB with Adafruit Pinguin to make a lovely and legible silkscreen.
  • Please note: The terminal blocks included with your product may be blue or black.

Resources

• Datasheet
• Thermocouple Tutorial

Package Contents

• 1x Thermocouple Amplifier MAX31855 breakout board (MAX6675 upgrade)
• 1x 6-pin header