1-Wire thermocouple-to-digital converters for multisensor installations

July 11, 2013 // By Graham Prophet
Maxim’s converters integrate all the functions required for a complete and highly accurate thermocouple-to-digital solution.

MAX31850/MAX31851 are cold-junction-compensated, 1-Wire thermocouple-to-digital converters. The devices achieve ±2.0°C accuracy (not including sensor nonlinearity) while integrating all of the functions required for a complete thermocouple-to-digital solution. The MAX31850/MAX31851’s 1-Wire interface allows multiple sensor locations to communicate and draw power over a single data line, greatly simplifying wiring requirements. Designers can use the MAX31850 or MAX31851 instead of multiple discrete components for accurate temperature measurement in medical, industrial, and solar applications.

Because thermocouple output voltages are small and cold-junction compensation is needed to achieve accurate results, the digitisation of thermocouple signals can be a challenge. MAX31850/MAX31851 are the industry’s first solution to integrate a discrete analogue-to-digital converter (ADC), a highly accurate reference, a temperature sensor for cold-junction compensation, and a 1-Wire bus interface into a single chip. The converters operate with several types of thermocouples, speeding system design, lowering system cost, and reducing the bill of materials (BOM). The MAX31850/MAX31851 also identify open or shorted thermocouples that could result in erroneous temperature readings or system faults. A microcontroller can read the fault status at any time to help ensure uptime and prevent costly repairs. A large number of devices can reside on the same communication bus. Their four dedicated address pins uniquely identify up to 16 sensor locations. MAX31850 is available for K, J, N, T, and E thermocouple types and the MAX31851 is available for R and S thermocouple types.

In a 10-pin, exposed-pad TDFN package (3 x 4 x 0.75 mm), and specified over the -40°C to +125°C temperature range, pricing starts at $3.10 (1000).

Maxim Integrated, www.maxim-ic.com