Analog Front End (AFE) for Sensing Temperature in Smart Grid Applications Using RTD Reference Design


Design files


This reference design enables up to 4 Resistor Temperature Detectors (RTD) to be connected through one ADC in manner such that the solution is both compact and modular. Communication from the ADC to the processor is though an SPI interface. If 8 RTDs are required for an application, simply connect up one more of these modules. This solution is flexible to where it can handle 2 wire, 3 wire or 4 wire type RTDs.

  • Based on the ADS1248 24-Bit Delta-Sigma (ΔΣ) ADC With Internal PGA and Selectable Gain up to 128
  • Can Measure 2-, 3-, or 4-Wire RTD Inputs
  • Multiplexer (Analog Switch) to Switch Excitation Currents for Four RTD Inputs
  • Uses Ratiometric Measurement for Higher Accuracy
  • Accuracy < ±2°C Without Calibration for Pt100
  • I2C I/O Expander for ADC Interface Control and Excitation Current Switching Provided (No External I/Os Required)
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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.

TIDU575.PDF (4974 K)

Reference design overview and verified performance test data


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

TIDRCL2.ZIP (3158 K)

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

TIDC853.ZIP (477 K)

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

TIDRCG6.PDF (2249 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Analog switches & muxes

TS3A50173.3-V, 4:1, 2-channel general-purpose analog multiplexer

Data sheet: PDF | HTML
I2C general-purpose I/Os (GPIOs)

TCA6408A8-bit translating 1.65- to 5.5-V I2C/SMBus I/O expander with interrupt, reset & config registers

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
N-channel MOSFETs

CSD17571Q230-V, N channel NexFET™ power MOSFET, single SON 2 mm x 2 mm, 29 mOhm

Data sheet: PDF | HTML
Precision ADCs (<=10MSPS)

ADS114816-bit 2-kSPS ADC with PGA, reference and IDAC for precision sensor measurement

Data sheet: PDF | HTML
Precision ADCs (<=10MSPS)

ADS124824-bit, 2-kSPS, eight-channel delta-sigma ADC for precision sensor measurement

Data sheet: PDF | HTML

Start development


Code example or demo

TIDA-00110 Code Examples — TIDC765.PDF (481 K)

GUI for evaluation module (EVM)

TIDA-00110 RTD GUI — TIDC854.ZIP (1814 K)

lock = Requires export approval (1 minute)
Support software

TIDA-00110 Temperature Measurement With RTD for Transformer/Generator Protection — TIDC855.ZIP (1938 K)

lock = Requires export approval (1 minute)

Technical documentation

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Type Title Date
* Design guide Analog Front End for Sensing Temperature in Smart Grid Applications Using RTD Dec. 22, 2014
Technical article Check out latest reference design of Analog Front End for Sensing Temperature in Grid Infrastructure Using RTD Jan. 13, 2015

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