Analog Linearized 3-Wire PT1000 RTD to 2-Wire 4-20mA Current Loop Transmitter Reference Design
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Key Document


This design features a single-chip solution to linearize and transmit a 3-wire PT1000 RTD over the industry standard 2-wire 4-20mA current loop.  The design was configured for a -50°C to 250°C  temperature range, but other temperature ranges can be achieved by adjusting the component values as discussed in the Theory of Operation section of the reference design guide.  Unadjusted design accuracy was measured to be less than 0.15°C over the selected RTD temperature span.

  • Input:  3-Wire PT1000 RTD
  • RTD Temperature Range:  -50°C to 250°C
  • Output:  2-Wire 4-20mA Current Loop
  • Includes analog RTD sensor linearization for >40x linearity improvement over end-point fit
  • Reference design includes theory, calculated error analysis, component selection, PCB layout, and measured results

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Schematic/Block Diagram

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TI Devices (1)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
XTR112  4-20mA Current Transmitters with Sensor Excitation (2 x 250-µA) and Linearization   Special function amplifiers  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
XTR112 Download Download

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User guides (1)
Title Type Size (KB) Date
PDF 997 09 Nov 2015
Design files (3)
Title Type Size (KB) Date
PDF 300 12 Jan 2018
PDF 210 03 Dec 2015
ZIP 1130 03 Dec 2015

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