MAX31856: Explaining the Thermocouple Digital Converter

A thermocouple is an essential component in many temperature sensors. Also, it is a sensitive device that requires the support of a top-quality digital converter. The Adafruit MAX31856 with cold-compensation reference is such an amplifier. In this article, we will check out the key features, pin configuration, benefits, features, and other converter properties.  

What is MAX31856?

It is a universal thermocouple amplifier by Adafruit with a cold-junction compensation feature for use with thermocouples. Primarily, it enables signal digitization from all types of thermocouples to give output data in the form of degrees celsius.

The converter is capable of providing temperature resolution up to 0.0078125°C.

Furthermore, the maximum temperature readings can go to a high of +1800°C and a low of -210°C. But, this range is dependent on the thermocouple type.  

MAX31856 Pin Configuration

Here is the pin configuration of the component:

MAX31856 Block Diagram

Below is a block diagram illustrating the operation principle of the thermocouple digital converter:

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Benefits and Features

A thermocouple in a heater. 

• The thermocouple amplifier guarantees high precision thermocouple temperature readings.
• Also, it features an internal cold-junction compensation accuracy of ±0.7°C and comes in a TSSOP-14 package.
• Additionally, it is a 19-bit device with a thermocouple temperature resolution of 0.0078125°C.
• It also enables automatic linearization correction for a wide range of thermocouple types.
• Moreover, it has a noise rejection filtering feature of 50Hz/60Hz to improve the system performance.
• It will also detect open thermocouples and has a fault detection system for over and under temperatures.
• With the chip, troubleshooting and system fault management are significantly easy.
• Besides, it also has a ±45V input protection feature to enhance system performance.
• It enables the thermocouple detection of a full scale and linearity error of ±0.15% for almost any thermocouple type.
• Lastly, it sports an SPI-compatible interface enabling thermocouple type selection. This feature is also imperative in the fault detection and conversion setup procedure.

Associated Development Tools

A thermocouple in the heater

The following are the development tools that work hand in hand with this amplifier:

1. Maxim Integrated MAX31856EVSYS Evaluation System: It enables access to the hardware and software components necessary to evaluate the converter. The tool also estimates the K-Type Thermocouples and is RoHS compliant.
2. Maxim Integrated MAX31856PMB1 Pmod™ Evaluation Board: It is significant in interfacing the MAX31856 RTD-to-Digital Converter with any component/system with Pmod ports. Also, it enables the use of the MAX31856 4-wire SPI interface while providing a 3.3V power supply to the converter.

Applications of MAX31856

Max31856 is useful in industrial ovens. 

• It's essential in industrial equipment, furnaces, and temperature controllers.
• Also, it’s useful in industrial ovens and environmental chambers for temperature control.

MAX31856 Application Circuit

Circuit diagram

MAX31856 vs. MAX31855

Thermocouples heads.

Both digital converters support the same types of thermocouples. These include the E, J, K, N, R, S, and T thermocouples. However, while MAX31856 supports B-type thermocouples, the MAX31855 does not. Primarily this is the main difference between the two.  

Summary

Above is a detailed explanation of all the key features and applications of the MAX31856 digital convertor. While it is primarily useful in industrial applications, you can still use it in any project requiring temperature control. That's all on the thermocouple amplifier, but if you have any queries, feel free to reach out.