Highly-Accurate, Loop-Powered, 4mA to 20mA Field Transmitter With HART® Modem Reference Design


Design files


This reference design provides a solution for a loop-powered, highly-accurate, field (sensor) transmitter with a HART® modem. The design uses a partially-discrete 4-mA to 20-mA current transmitter, HART modem, microcontroller, and power conditioning blocks in realizing a smart field transmitter design. The design is compliant with the HART FSK Physical Layer Specification and has been registered with FieldComm Group™.

  • Loop-powered, 4-mA to 20-mA current transmitter with DAC8740H HART modem and onboard power conditioning blocks
  • Less than 0.1% FSR total unadjusted error at room temperature
  • External protection circuitry with reverse polarity protection
  • Compliant with HART FSK Physical Layer Specification and registered HART device

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.


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


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


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


PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Precision DACs (<=10MSPS)

DAC8740HHART®, FOUNDATION Fieldbus™, and PROFIBUS PA-compliant modem with UART interface

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

DAC883016-bit, single-channel, ultra-low power, voltage output DAC

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

TPS7A410150-mA, 50-V, low-IQ, adjustable low-dropout voltage regulator with enable

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

TPS7B69-Q1Automotive 150-mA, off-battery (40-V), high-PSRR, low-IQ, low-dropout voltage regulator

Data sheet: PDF | HTML
MSP430 microcontrollers

MSP430FR596916 MHz MCU with 64KB FRAM, 2KB SRAM, AES, 12-bit ADC, comparator, DMA, UART/SPI/I2C, timer

Data sheet: PDF | HTML
Precision op amps (Vos<1mV)

OPA3331.8-V, 17-µA, microPower, precision, zero-drift CMOS op amp

Data sheet: PDF | HTML
Precision op amps (Vos<1mV)

OPA335Single 0.05uV/C max, single-supply CMOS operational amplifier

Data sheet: PDF
Series voltage references

LM41320.05% 20-ppm/°C drift precision series voltage reference with shutdown enable

Data sheet: PDF | HTML

Technical documentation

= Top documentation selected by TI
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Type Title Date
* Design guide High Accuracy Loop-Powered 4-to-20mA Field Transmitter w/ HART Modem Ref Design Dec. 20, 2017
Technical article How to HART-enable your analog input module Apr. 02, 2018
Technical article Improve your field transmitter designs with HART Feb. 22, 2018
Technical article Back to the basics: what is HART protocol and how does it work? Jan. 26, 2018

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