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

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!

Infographic - A Guide to Inductive Sensing.pdf