HVAC Coil Airflow Sensor Reference Design for Predictive Maintenance in Air Filter Replacement


Design files


This design provides a reference for monitoring airflow efficiency and temperature through heat ventilation and air conditioner (HVAC) systems. The reference design is used in conjunction with solid state relays and piezoelectric vibration sensors to monitor and react accordingly to low airflow and low temperature conditions through the air handler. The system also includes a calibration algorithm for consistent performance across all system setups.

  • Low temperature condenser cutoff
  • One button system calibration
  • Designed to work with air handler 24 VAC transformer
  • 14.08 mA current consumption when running
  • Operating conditions: -40°C to 85°C
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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.


Reference design overview and verified performance test data

TIDRNO4.PDF (1950 K)

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

TIDRNO8.ZIP (2121 K)

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


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

TIDRNO7.PDF (2425 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

MSP430 microcontrollers

MSP430FR231116-MHz integrated analog microcontroller with 3.75-KB FRAM, OpAmp, TIA, comparator w/DAC, 10-bit ADC

Data sheet: PDF | HTML
Analog temperature sensors

LMT841.5V-Capable, 10 uA Analog Output Temperature Sensor in SC70 and TO-92

Data sheet: PDF | HTML
Buck converters (integrated switch)

TPS54013.5V to 42V Input, 0.5 A Step Down Converter

Data sheet: PDF | HTML
ESD protection diodes

TPD1E10B0612-pF, ±5.5V, ±30-kV ESD protection diode in 0402 and SOD-523 package

Data sheet: PDF | HTML
General-purpose op amps

TLV4313Quad, 5.5-V, 1-MHz, low quiescent current (65-μA), RRIO operational amplifier

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

LP2985-N150-mA, 16-V, low-dropout voltage regulator with enable

Data sheet: PDF | HTML
NOR gates

SN74LVC1G27Single 3-input, 1.65-V to 5.5-V NOR gate

Data sheet: PDF

Start development


Technical documentation

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Type Title Date
* Design guide HVAC Coil Airflow Sensor for Predictive Maintenance in Air Filter Replacement (Rev. A) Oct. 25, 2016
Technical article Predictive maintenance solutions for HVAC filter replacement – part 2 PDF | HTML Dec. 08, 2016
Technical article Predictive maintenance solutions for HVAC filter replacement – part 1 PDF | HTML Nov. 14, 2016
White paper Making factories smarter, more productive through predictive maintenance Nov. 02, 2016
Technical article Trends in building automation: predictive maintenance PDF | HTML Nov. 01, 2016

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