±0.5°C 2-Wire Galvanically Isolated IC Temp Sensor with Pulse Count Interface Reference Design


Design files


In order to provide system designers a new cost-effective and easy alternative to assured precision temperature measurement, this reference design discusses the new tiny 2-pin digital output IC temperature sensor with single wire pulse count interface that enhances reliability and greatly simplifies the design of galvanic isolation architecture for sending both power and unidirectional data through same low profile transformer and remote operation. In addition, with fewer error sources, computation of error budget is easier. Cost budgets, accuracy, size and simplicity of interfacing with other circuit elements are main factors in selecting a sensor to do a job and this reference design system tremendously helps in meeting all these requirements. With less-than 0.25°C maximum measured error over temperature range -50°C to 150°C, functional isolation of 400VRMS and IEC61000-4-4 pre-compliance testing, this design significantly reduces the design time for development of high-accuracy temperature measurement systems.

  • Allows Single Low-Profile Transformer for Power and Data Isolation While Eliminating the Need for Optocoupler or Digital Isolator on Data Line
  • Power and Data Coexist on 2–Wire Interface for Remote Temperature Sensing Across Isolation
  • No Need of System Level Calibration Unlike Thermistors
  • Replacement for RTDs and NTC or PTC Thermistors
  • Eliminates High-Precision Active or Passive Components
  • Functional Isolation of 400 VRMS and Dielectric up to 2500-V AC for 60 seconds
  • Pre-Compliance Testing: Meets IEC61000-4-4 EFT (Level 4): ±2 kV – Class-A
  • Accuracy Over Temperature:
    • Measured Error Using LUT: < 0.25ºC (-35ºC to 150ºC)
    • Measured Error Using 1st Order Transfer Function: < 0.25ºC (15ºC to 100ºC)
    • Guaranteed Limits from LMT01 Datasheet Using LUT: < 0.5 max. (-20ºC to 90ºC), 0.62 max. (90ºC to 150ºC), < 0.7 max. (-50ºC to -20ºC)
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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.

TIDUB78B.PDF (1998 K)

Reference design overview and verified performance test data

TIDCBK1.ZIP (2135 K)

Detailed schematic diagram for design layout and components


Detailed schematic diagram for design layout and components


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


Detailed overview of design layout for component placement


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

TIDRJB7.PDF (1359 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Digital temperature sensors

LMT010.5°C Accurate 2-pin Temperature Sensor with a Pulse Train Interface

Data sheet: PDF | HTML
ESD protection diodes

TPD2E001Dual 1.5-pF, 5.5-V, ±8-kV ESD protection diode with 1-nA max leakage & VCC pin for USB 2.0

Data sheet: PDF | HTML
MSP430 microcontrollers

MSP430F552825 MHz MCU with 128KB Flash, 8KB SRAM, 12-bit ADC, comparator, DMA, UART/SPI/I2C, USB, HW multiplier

Data sheet: PDF | HTML
Transformer drivers

SN6505BLow-noise, 1-A, 420-kHz transformer driver with soft start for isolated power supplies

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide 2-Wire Isolated Temperature Sensor Design Guide (Rev. B) Jun. 20, 2016

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