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


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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Schematic/Block Diagram

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Design Files

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TI Devices (4)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
LMT01  0.5°C Accurate 2-pin Temperature Sensor with a Pulse Train Interface  Temperature sensors  Sample & Buy View Design Kits & Evaluation Modules
MSP430F5528  25 MHz MCU with 128KB Flash, 8KB SRAM, 12-bit ADC, comparator, DMA, UART/SPI/I2C, USB, HW multiplier  Microcontrollers (MCUs)  Sample & Buy View Design Kits & Evaluation Modules
SN6505B  Low-noise, 1-A, 420-kHz transformer driver with soft start for isolated power supplies  Power for signal isolators  Sample & Buy View Design Kits & Evaluation Modules
TPD2E001  Dual 1.5-pF, 5.5-V, ±8-kV ESD protection diode with 1-nA max leakage & VCC pin for USB 2.0  Circuit protection ICs  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
LMT01 Download -
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MSP430F5528 Download Download
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(ZQE) | 80 Download -
SN6505B Download Download
TPD2E001 Download -
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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 1998 20 Jun 2016
Design files (6)
Title Type Size (KB) Date
ZIP 2135 09 Dec 2015
ZIP 712 09 Dec 2015
PDF 1359 09 Dec 2015
PDF 164 09 Dec 2015
PDF 59 09 Dec 2015
PDF 535 09 Dec 2015

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