June Birth Magoncia

user Electronics Engineer

city Innovuze Solutions, Inc.

  • MCP9600 Thermocouple EMF to Temperature Converter

  • Created: Feb 02, 2016

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A thermocouple is a device that acts as a temperature to voltage transducer. It is composed of two different wires. One end of the wires is welded together. This end is referred as junction end. The other end of the thermocouple (end of two wires that is not joined) is referred as reference end. When the junction end experience changes in temperature, an electromotive force (EMF) occurs at the reference end of the thermocouple. That EMF serves as a reference for devices like MCP9600 to convert the thermocouple EMF reading to a degree Celsius unit.

In this circuit, the type K thermocouple is inserted at the input side of the type K thermocouple adapter or connector, PCC-SMP-K-100. The thermocouple adapter is connected to the thermocouple input pins (VIN+, VIN-) through FB1, FB2, and C7 network. The MCP9600 reads the voltage across the thermocouple input pins and convert it to degree Celsius unit. After the conversion, the MCP9600 serially transmits the temperature data to the PIC18F2520T-I/SO microcontroller over the I2C bus. The PIC18F2520T-I/SO microcontroller sends the temperature reading to a computer over the universal serial bus. Also, the temperature can be data-logged using the microchip thermal management software graphical user interface. The alert pins (Alert1-Alert4) of the MCP9600 are user-programmable push-pull outputs, which can be used to detect rising or falling temperatures. These pins output signals when the temperature exceeds the user-programmed temperature alert limit.

The MCP9600 device is not just limited to type K thermocouples. It can also support other types of thermocouple by replacing the thermocouple connector or adapter with the corresponding thermocouple type. The thermocouple sensor register must be configured also to select the appropriate internal digital filter. This circuit is ideal for systems wherein low power consumption is necessary. The MCP9600 device operates within the range of 2.7V to 5.5V and only consumes 500uA of current. This design can be used in different applications such as industrial equipment thermal management, ovens, industrial engine thermal monitor, temperature detection racks, etc.