Analog Front End for Motor Electronic Overload Relays with Enhanced Current Range


Design files


This reference design is the analog front end (AFE) for an electronic overload relay, used for monitoring and protecting motors from overcurrent or undercurrent events. It is an ideal tool for developers creating overload relays for sensitive AC motors in industrial applications. This programmable gain amplifier (PGA) based analog front end is intended to be an easy evaluation platform for an accurate, industry-leading 10:1 full load ampere (FLA) range and is repeatable over a -10 to +70°C temperature range.

  • Wide FLA of 10:1 which dramatically reduces the number of units required on-hand
  • Current measurement accuracies of <2% over entire 10:1 measurement range from no load to locked rotor current
  • Ambient insensitivity from -10 to +70°C
  • Robust design that prevents phase reversal in overdrive conditions and high electrostatic discharge (ESD) protection (3-kV HBM)
??image.gallery.download_en_US?? View video with transcript Video

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.

TIDU267.PDF (4179 K)

Reference design overview and verified performance test data

TIDC346.ZIP (6894 K)

Detailed schematic diagram for design layout and components

TIDR487.PDF (355 K)

Detailed schematic diagram for design layout and components

TIDR488.PDF (97 K)

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

TIDC345.ZIP (797 K)

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


Includes TI products in the design and potential alternatives.

Analog temperature sensors

LM62±2°C analog output temperature sensor, with 15.6mV/°C gain

Data sheet: PDF
Isolated DC/DC converters & modules

LM50177.5-100V Wide Vin, 600mA Constant On-Time Synchronous Buck Regulator

Data sheet: PDF | HTML
Isolated DC/DC converters & modules

TPS550102.95V To 6V Input, 2W, Isolated DC/DC Converter with Integrated FETS

Data sheet: PDF | HTML
Isolated RS-485 transceivers

ISO117640-Mbps, half-duplex, isolated RS-485 & RS-422 transceiver

Data sheet: PDF | HTML
N-channel MOSFETs

CSD18537NKCS60-V, N channel NexFET™ power MOSFET, single TO-220, 14 mOhm

Data sheet: PDF | HTML
Programmable & variable gain amplifiers (PGAs & VGAs)

PGA116Zero-Drift, 100-µV offset, 12-nV/√Hz noise, RRO (binary gain) programmable gain amp w

Data sheet: PDF | HTML
Shunt voltage references

LM4041BAdjustable, precision micropower shunt voltage reference with 0.2% accuracy

Data sheet: PDF

Technical documentation

= Top documentation selected by TI
No results found. Please clear your search and try again.
View all 1
Type Title Date
* Design guide Analog Front End for Motor Electronic Overload Relays Design Guid Mar. 21, 2014

Support & training

TI E2E™ forums with technical support from TI engineers

View all forum topics

Content is provided "as is" by TI and community contributors and does not constitute TI specifications. See terms of use.

If you have questions about quality, packaging or ordering TI products, see TI support. ​​​​​​​​