Isolated Loop Powered Thermocouple Transmitter Reference Design


Design files


The Isolated Loop powered Thermocouple Transmitter reference design is a system solution providing precision K-type thermocouple measurements for 4 to 20-mA isolated current-loop applications. This design is intended as an evaluation module for users to fast prototype and develop end-products for process-control and factory-automation. Potential challenges with thermocouples as a temperature sensor include tiny voltage outputs, low sensitivity and nonlinearity; in addition, because in industrial environments ground potential differences higher than 100V are common, thermocouple and signal conditioning circuitry must be galvanically isolated. The design files include design considerations, block diagrams, schematics, Bill of Materials (BOM), layer plots, Altium files, Gerber Files, and MSP430 Firmware.

Watch the TIDA-00349 Overview video, covering the same isolated power topology as used in the TIDA-00189 NOW

  • Sensor input compatible with k-Type Thermocouple  probes ( -200°C to +1375°C)
  • Operating temperature of the circuit -40°C to +85°C
  • Implements Cold Junction compensation (RTD based)
  • Front End accuracy < 0.5°C (-200°C to +270°C) and < 0.15% (270°C to +1375°C)
  • 4 to 20mA current loop output signal
  • Design to meet IEC 61000-4-5
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDU449B.PDF (8443 K)

Reference design overview and verified performance test data

TIDRB93.PDF (948 K)

Detailed schematic diagram for design layout and components

TIDRB94.PDF (72 K)

Complete listing of design components, reference designators, and manufacturers/part numbers

TIDRB95.PDF (342 K)

Detailed overview of design layout for component placement

TIDRB98.ZIP (1416 K)

Files used for 3D models or 2D drawings of IC components

TIDC700.ZIP (484 K)

Design file that contains information on physical board layer of design PCB

TIDRB96.PDF (3498 K)

PCB layer plot file used for generating PCB design layout

TIDRB97.PDF (6231 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

AC/DC & DC/DC converters (integrated FET)

TPS6040260mA Charge Pump Voltage Inverter with Fixed 50kHz Operation

Data sheet: PDF | HTML
Linear & low-dropout (LDO) regulators

TPS7A16100-mA, 60-V, ultra-low-IQ, low-dropout (LDO) voltage regulator with power good and enable

Data sheet: PDF | HTML
MSP430 microcontrollers

MSP430F517225 MHz MCU with 32KB Flash, 2KB SRAM, 10-bit ADC, comparator, DMA, 16-bit High Resolution timer

Data sheet: PDF | HTML
Noninverting buffers & drivers

SN74LVC125AFour-channel 1.65V-to-3.6V buffers with 3-state outputs

Data sheet: PDF | HTML
Precision ADCs

ADS122024-bit, 2-kSPS, four-channel, low-power, delta-sigma ADC with PGA, VREF, SPI and two IDACs

Data sheet: PDF | HTML
Precision DACs (≤10 MSPS)

DAC161P997Single-Wire 16-bit DAC for 4-20mA Loops

Data sheet: PDF | HTML

Start development


Technical documentation

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Type Title Date
* Design guide Isolated Loop Powered Thermocouple Transmitter Design Guide (Rev. B) Jul. 19, 2016
Technical article What’s next for Industry 4.0? The best new technologies shaping the future of smar PDF | HTML Nov. 07, 2016

Related design resources

Reference designs

TIDA-00095 RTD Temperature Transmitter for 2-wire, 4 to 20-mA Current Loop Systems TIDA-00165 Small Form Factor, 2-Wire 4 to 20mA Current Loop RTD Temperature Transmitter Reference Design TIDA-00168 Thermocouple AFE Using RTD or Integrated Temperature Sensor for Cold Junction Compensation (CJC) TIDA-00247 Single Chip 2-Wire Loop Powered, 4 to 20mA Current Loop RTD Temperature Transmitter Reference Design TIDA-00459 Highly Efficient Power & Data Transmission for Isolated Low Power Applications Reference Design

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