Inductive sensing: Meet LDC, the industry’s first inductance-to-digital converter

Inductive sensing: Meet LDC, the industry’s first inductance-to-digital converter

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A revolution in sensing has begun! Today, TI announced the industry’s first inductance-to-digital converter (LDC), a true technology game changer for position and motion sensing. And I don’t say that lightly.

This is the first post in a new series here on Analog Wire, where I’ll explore TI’s new LDCs, which allow you to build inductive sensing solutions. Inductive sensing technology enables a host of smart and innovative sensing applications, limited only by your imagination and creativity.

What can I do with an LDC?

LDCs enable low-cost detection of metal and conductive targets in the presence of dust and dirt, while delivering sub-micron resolution. Some basic applications include axial, linear and angular position sensing. Springs, which are found in many systems, can also be used as sensors to measure compression, extension, and even twist.

Inductive sensing solutions built with LDCs deliver better performance and better reliability while reducing system cost and complexity. The infographic below shows several applications using inductive sensing.

<Click here to download a pdf of the image>

How do LDCs enable inductive sensing?

So how do LDCs work? An alternating magnetic field is generated by an oscillating LC tank; when a conductive material comes in the vicinity of the tank, eddy currents are generated in the metal or conductor. This creates losses in the tank and also changes the total inductance of the system.

Using the LC tank as a sensor, LDCs measure both the losses and the oscillation frequency of the tank. Losses in the tank are measured in terms of a resistor parallel to the coil, the parallel resonance impedance (Rp). The oscillation frequency of the tank is used to measure inductance.

The LDC1000, the first product introduced in our LDC family, provides 16 bits of Rp resolution and 24 bits of frequency resolution, with Rp in the range of 798Ω to 3.93MΩ and the tank frequency configurable from 5Khz to 5Mhz.

In my next post, I’ll talk more about the LDC1000 itself and the tools available to get started implementing inductive sensing in your design.

In the interim, you should check out these videos to see an LDC in action:

And if you want to experience LDC technology firsthand, the best way is with our evaluation module, the LDC1000EVM, which you can order today for only US$29. You have to see it to believe it!

Attachment: Infographic - A Guide to Inductive Sensing.pdf
  • Just a feedback that I cannot share this link on Facebook, your webserver somehow returns a "Forbidden" error for that.... See developers.facebook.com/.../object

  • If you click on the FB link on top of this page, it will post the link on your FB profile.

    Even copy and paste of the link in FB worked for me.

  • hi, the vdeio of LDC 1000: A revolution in sensing is not downloading...

  • @Thamballa, thanks for your interest in the video. I just clicked on both of the video links above, and they played for me using both Internet Explorer and Google Chrome browsers.  

  • sir i am interested in   this  product  LDC1000EVM   which is  very grate for my application  only thing ,what is the maximum distance that can sense if distance sensing application , i could not find any documents about the distance ,if it is there kindly send me the link  

  • Can you elaborate on the technical details of what the device is actually measuring to derive the "Proximity Data"?

  • @Jim: As explained in the above post, it is Rp and frequency. Refer to datasheet for formulas related to these parameters.

    @Mathivanan: maximum distance depends on coil diameter. As a rule of thumb, maximum distance is 50% of coil diameter.

    I will focus on these questions in my next post. Thanks for your questions.

  • Hi Murali, what if you have several coils, can you mux or do you need a chip for each one. Congratulations to you and the team, this is a great example of breakthrough technology

  • Thanks for the article Murali. Will I be able to get the evaluation module here in India?

  • sir

    Thank u for the reply and , i would like to know more details about application oriented ,

    i expect ur reply soon

  • Hi Soufiane, Thank you.

    Yes, with LDC1000, it will be one IC per Coil.

  • Hi Srinivas,

    Yes, you will have to order here:estore.ti.com/LDC1000EVM-Evaluation-Module-for-Inductance-to-Digital-Converter-with-Sample-PCB-Coil-P4694.aspx

  • Please post your questions related to LDC1000 here:e2e.ti.com/.../default.aspx

  • If I were to do the gear-count, suppose the gear plate is thin, then I would want to have a very low resolution because of vibration that may exist, right?

  • Depends on the coil diameter. For a ON/OFF o/p it should be fine.