• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Electrical Engineering News and Products

Electronics Engineering Resources, Articles, Forums, Tear Down Videos and Technical Electronics How-To's

  • Products / Components
    • Analog ICs
    • Battery Power
    • Connectors
    • Microcontrollers
    • Power Electronics
    • Sensors
    • Test and Measurement
    • Wire / Cable
  • Applications
    • 5G
    • Automotive/Transportation
    • EV Engineering
    • Industrial
    • IoT
    • Medical
    • Telecommunications
    • Wearables
    • Wireless
  • Learn
    • eBooks / Handbooks
    • EE Training Days
    • Tutorials
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • White Papers
    • Design Guide Library
    • Digital Issues
    • Engineering Diversity & Inclusion
    • LEAP Awards
    • Podcasts
    • DesignFast
  • Videos
    • EE Videos and Interviews
    • Teardown Videos
  • EE Forums
    • EDABoard.com
    • Electro-Tech-Online.com
  • Bill’s Blogs
  • Advertise
  • Subscribe

ICs for interfacing inductive sensors, Part 1

March 1, 2021 By Bill Schweber

Designers who use inductive proximity sensors have a choice of high-performance signal-conditioning interface ICs, each offering different sets of features, functions, and capabilities.

In the two preceding features (see Related EEWorld Content), we looked at the inductive proximity sensor and its basic operation but did not look at the electronic interface circuit for this widely used sensor. This follow-up feature looks at three different ICs which are specifically designed for this sensor. It will not be a recitation of the specifications except for a critical few as needed, as you can read the linked data sheets themselves. Instead will focus on their functions, I/O, and other interesting features and capabilities.

In inductive sensors with today’s circuitry and ICs, three coils are typically printed as copper traces on a printed circuit board (PC board), which may then be encapsulated for protection. They are arranged such that the transmitter coil induces a secondary voltage in the two receiver coils, which depends on the position of the metallic target above the coils. The signal which represents the target’s position over the coils is obtained by demodulating and processing the secondary voltages from the receiver coils. The target can be any kind of metal, such as aluminum, steel, or even a PC board with a printed copper layer.

Due to its accuracy and precision, inherent ruggedness, convenient form factor, and ease of attachment, as well as flexibility in target being sensed, inductive sensors are used widely used in industrial applications and especially in automobiles for functions such as measurements related to motor rotation and position, high-temperature air/water valve position, electronic power-steering position and torque, transmission-gear position, throttle and brake position, and active suspension.

We will look at three representative ICs from Texas Instruments, Renesas Electronics, and Microchip Technology, all qualified to AEC-Q100 for automotive use. This is not an exhaustive list, as there are other vendors with ICs which can be used and even the cited vendors have other inductive-sensor interface ICs with different feature sets and specifications in their portfolios.

Texas Instruments LDC1101 1.8-V High-Resolution, High-Speed Inductance-to-Digital Converter

This 3-mm × 3-mm 10-pin IC is a 1.8-V to 3.3-V, high-resolution inductance-to-digital converter which is configured by a microcontroller using a 4-pin SPI interface (Figure 1). The LDC1101 includes a threshold-compare function which can be dynamically updated while the device is running. For measurement beyond basic presence detection, even sub-micron distance resolution is possible with the proper arrangement.

inductive sensors
Fig 1: The Texas Instruments LDC1101 inductive proximity sensor interface IC can provide close-in sub-micron resolution or broader resolution at a distance. (Image: Texas Instruments)

This device can be used to make two related inductance-sensor measurements:

  • RP-measurement, which measures the equivalent parallel impedance of the sensor at its resonant frequency by measuring the energy loss of the sensor due to magnetic coupling with a conductive target.
  • Inductance (L)-measurement, a measurement the resonant frequency of the sensor, which is a function of sensor inductance, also influenced by magnetic coupling with a conductive target.

The LDC1101 features dual inductive measurement cores, allowing for greater 150 kilosamples/second (ksps) 16-bit RP and L measurements simultaneous with a high-resolution L measurement which can sample at higher than 180 ksps with a resolution of up to 24 bits. The obvious question is: which one should you measure, or perhaps you should measure both? The answer is a function of many factors including, but not limited to, these:

  • RP-measurements do not rely on an accurate reference clock and the device can perform RP-measurements without an external reference clock. This is an advantage in situations where a reference clock is not available, or where number of wires between the LDC and the microcontroller must be minimized.
  • The effect of temperature drift of the target’s metal for L-measurements is small compared to the effect on RP-measurements. To account for the change in resistivity of the sensor conducting metal, temperature compensation is typically required for most applications that employ RP measurement.
  • Most metal types can be equally well-measured with L or RP. However, there are some magnetic materials where the L response at certain frequencies is significantly smaller than the RP response. For those materials, RP is likely a more suitable choice.

The 59-page LDC1101 data sheet is detailed with specifications, configuration, and set-up information as expected. It also includes circuit analysis, modeling, and equations for setting various factors such as time constants, different sensing situations, size and material of different targets and how to accommodate them, and also links to many other relevant application notes and blogs.

The next part of this article looks at ICs from Renesas and Microchip Technology.

 

Related EE World Content

What are inductive proximity sensors? Part 1
What are inductive proximity sensors, Part 2
LVDT electronics, Part 1: Excitation and demodulation
LVDT electronics, Part 2: Interface circuitry

References

Texas Instruments
“LDC1101 1.8-V High-Resolution, High-Speed Inductance-to-Digital Converter” (data sheet)
“Inductive sensing: Should I measure L, RP or both?”
TIDA-00563, “Inductive Proximity Switch BoosterPack Reference Design”
Renesas Electronics
“IPS2200 Inductive Position Sensor” (data sheet)
Microchip Technology
“Robust, Low-Cost and Noise-Immune Motion-Sensing Inductive Sensors”
“LX3301A Inductive Sensor Interface IC with Embedded MCU”

You Might Also Like

Filed Under: FAQ, Featured, Sensor Tips Tagged With: FAQ

Primary Sidebar

EE Engineering Training Days

engineering

Featured Contributions

Five challenges for developing next-generation ADAS and autonomous vehicles

Robust design for Variable Frequency Drives and starters

Meeting demand for hidden wearables via Schottky rectifiers

GaN reliability milestones break through the silicon ceiling

From extreme to mainstream: how industrial connectors are evolving to meet today’s harsh demands

More Featured Contributions

EE Tech Toolbox

“ee
Tech Toolbox: 5G Technology
This Tech Toolbox covers the basics of 5G technology plus a story about how engineers designed and built a prototype DSL router mostly from old cellphone parts. Download this first 5G/wired/wireless communications Tech Toolbox to learn more!

EE Learning Center

EE Learning Center
“ee
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for EE professionals.
“bills
contribute

R&D World Podcasts

R&D 100 Episode 10
See More >

Sponsored Content

Advanced Embedded Systems Debug with Jitter and Real-Time Eye Analysis

Connectors Enabling the Evolution of AR/VR/MR Devices

Award-Winning Thermal Management for 5G Designs

Making Rugged and Reliable Connections

Omron’s systematic approach to a better PCB connector

Looking for an Excellent Resource on RF & Microwave Power Measurements? Read This eBook

More Sponsored Content >>

RSS Current EDABoard.com discussions

  • problem connecting to my xilinx device VIA global IP
  • Testing 5kW Grid Tied inverter over 200-253VAC
  • Mean offset increase in post-layout simulation of clocked comparator
  • Getting different output for op amp circuit
  • dc-dc converter in series

RSS Current Electro-Tech-Online.com Discussions

  • Back to the old BASIC days
  • using a RTC in SF basic
  • what's it's name
  • What is correct names for GOOD user friendly circuit drawing program?
  • Curved lines in PCB design
Search Millions of Parts from Thousands of Suppliers.

Search Now!
design fast globle

Footer

EE World Online

EE WORLD ONLINE NETWORK

  • 5G Technology World
  • Analog IC Tips
  • Battery Power Tips
  • Connector Tips
  • DesignFast
  • EDABoard Forums
  • Electro-Tech-Online Forums
  • Engineer's Garage
  • EV Engineering
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips

EE WORLD ONLINE

  • Subscribe to our newsletter
  • Teardown Videos
  • Advertise with us
  • Contact us
  • About Us

Copyright © 2025 · WTWH Media LLC and its licensors. All rights reserved.
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

Privacy Policy