Adafruit
Thermocouple Amplifier MAX31855 breakout board (MAX6675 upgrade)
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
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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