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The MAX31855 Thermocouple Amplifier Breakout converts K-type thermocouple readings into digital data via SPI, handling cold-junction compensation automatical...

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The MAX31855 Thermocouple Amplifier Breakout converts K-type thermocouple readings into digital data via SPI, handling cold-junction compensation automatically. It measures temperatures from −200°C to +1350°C in 0.25°C increments, making it suitable for a wide range of temperature monitoring applications.

The breakout includes the MAX31855K chip, a 3.3 V regulator with 10 µF bypass capacitors, and level-shifting circuitry for 3.3–5 V compatibility. It comes with a 2-pin terminal block for the thermocouple connection and a pin header for breadboard use.

Key Features

  • K-Type Thermocouple Interface – Digital SPI output with cold-junction compensation
  • Wide Temperature Range – −200°C to +1350°C in 0.25°C increments
  • 3.3–5 V Compatible – On-board regulator and level shifting for flexible logic levels
  • SPI Interface – Requires only 3 digital I/O pins
  • Internal Temperature Sensor – Built-in cold-junction temperature reading
  • Fully Assembled – Tested and ready to use with included terminal block and header

Specifications

  • IC – MAX31855K (replaces discontinued MAX6675)
  • Thermocouple Type – K-type only
  • Temperature Range – −200°C to +1350°C
  • Resolution – 0.25°C
  • Accuracy – ±2°C to ±6°C (typical for K-type thermocouples)
  • Interface – SPI (3 digital pins)
  • Supply Voltage – 3.3–5 V

Ideal For

  • High-temperature monitoring (ovens, kilns, furnaces)
  • Industrial process temperature measurement
  • 3D printer hotend monitoring
  • Arduino and microcontroller temperature logging

Package Contents

  • 1× MAX31855 Thermocouple Amplifier Breakout (assembled and tested)
  • 1× 2-pin terminal block
  • 1× Pin header
Note: The MAX31855 is not pin-compatible or code-compatible with the older MAX6675. Existing MAX6675 designs will require adjustment. A K-type thermocouple is required and sold separately.

Resources

Jargon buster

Plain-language definitions for the technical terms used above.

breakout
A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.
Cold-junction compensation
Cold-junction compensation corrects for the temperature at the point where a thermocouple connects to the electronics. It matters because thermocouples measure temperature differences, so this correction is needed for more accurate real-world temperature readings.
K-Type
K-Type refers to a common thermocouple probe type made from specific metal alloys and suited to very high temperature measurement. It matters because the amplifier and the probe type must match; a K-Type amplifier is intended for K-Type thermocouples, not every thermocouple style.
microcontroller
A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.
SPI
A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.
Terminal block
A terminal block is a connector that joins wires together in a neat, removable, or serviceable way, usually clamping each wire under a screw or spring instead of soldering. It makes it easier to connect, change, or service wiring without permanent joints.
Thermocouple
A temperature sensor made from two different metals that produces a very small voltage depending on temperature. Because the signal is tiny, it usually needs careful amplification and accurate measurement hardware.
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