Thermocouple Sensor Conditioning Shouldn’t Make You “Hot Under the Collar”
Thermocouple Sensor Conditioning ICs provide an integrated, “plug and play” solution that simplifies the design of your application
Thermocouples are a type of sensor used to measure temperature in applications that are required to operate in harsh and extreme environments. The thermocouple is one of the oldest electronic temperature sensing devices and is widely used in a variety of markets including industrial, petrochemical, power and automotive. They are also commonly found in a variety of consumer products like coffee/espresso machines, inductive cooktops, and ovens.
Thermocouples are popular because they have the following advantages:
- Wide temperature range (from below –250°C to above 1800°C)
- Rugged performance (even in the presence of vibration and dirt)
- Simple design
- Self-powered (no voltage or current excitation required)
- Fast thermal response
- Accurately capture temperature spikes
Despite their many advantages, they have some drawbacks, one of which is that long thermocouple wires can unintentionally act as an antenna, picking up electrical noise from a variety of sources. This noise will be coupled to the thermocouple wires requiring precision signal conditioning circuitry to filter out this common mode noise. However, if the amplitude of this signal is too high, it can interfere with the operation of the circuits. The voltage signal generated by a thermocouple is very small (tens of millivolts). Measuring a signal this small in the presence of high amplitude common-mode noise requires a high-performance analog front-end, which can be difficult and expensive to design using up to 20 discrete components.
Simpler plug’n’play solution
A simpler alternative is to instead use our MCP9600 or MCP9601 conditioning ICs (Figure 1). These provide an integrated, “plug and play” solution that simplifies the design of your application. Once connected to a thermocouple these ICs immediately provide an accurate temperature reading (in degrees Celsius) via an onboard I2C interface.
The MCP9600 and MCP9601 combine precision instrumentation, an accurate temperature sensor and a high-resolution Analog-to-Digital Converter (ADC) with a math engine that has been preprogrammed with the firmware needed to support many different types of thermocouples (K, J, T, N, S, E, B and R). They also have integrated cold-junction compensation to calculate the “hot” junction temperature of a thermocouple, meaning you don’t need thermal design expertise in order to precisely measure the reference temperature of the “cold” junction.
Other features of the MCP9600/MCP9601 include a temperature-data digital filter, which minimizes the effects of temperature fluctuations, system noise and electromagnetic interference. The shutdown modes reduce overall system power consumption, while the four user-programmable temperature alert outputs reduce the system microcontroller’s overhead and code space, further simplifying designs. These ICs are available in a 5 mm × 5 mm, 20-lead MQFN package, which helps you to reduce board space and manufacturing costs.
We also provide the MCP9600 Thermocouple IC Evaluation Board (ADM00665) to help you get your thermocouple application up and running quickly. The MCP9600 and MCP9601 are ideal if you’re looking for a flexible, easy-to-use, integrated thermocouple signal conditioning solution that can reduce development risk and speed up the time-to-market for your product.
Visit our Thermocouple Conditioning ICs page for more information.