Texas Instruments invented a new Data Converter category

17 September, 2013

The new inductive sensing from Texas Instruments is a contactless sensing technology that can be used to measure the position, motion, or composition of a metal or conductive target, as well as detect the compression, extension or twist of a spring

Inductance-to-digital converter revolutionizes position and motion sensing

Many options for LDC inductive sensing
Many options for LDC inductive sensing

Texas Instruments (TI) unveiled this week the industry’s first inductance-to-digital converter. It is a new data converter category that uses coils and springs as inductive sensors to deliver higher resolution and greater flexibility than existing sensing solutions at a lower system cost. Inductive sensing is a contactless sensing technology that can be used to measure the position, motion, or composition of a metal or conductive target, as well as detect the compression, extension or twist of a spring.

The new sensor is based on well known phenomena: An AC current flowing through a coil will generate an AC magnetic field. If a conductive material, such as a metal target, is brought into the vicinity of the coil, this magnetic field will induce circulating currents (eddy currents) on the surface of the target. These eddy currents are a function of the distance, size, and composition of the target.

LDC1000-CHIPThese eddy currents then generate their own magnetic field, which opposes the original field generated by the coil. This mechanism is best compared to a transformer, where the coil is the primary core and the eddy current
is the secondary core. The inductive coupling between both cores depends on distance and shape. Hence the resistance and inductance of the secondary core (Eddy current), shows up as a distant dependent resistive and
inductive component on the primary side (coil). Measuring these effects on the primary side, produce accurate data about the position and movement of the target.

Applications for inductive sensing (LDC) range from simple push buttons, knobs, and on/off switches to high-resolution heart rate monitors, turbine flow meters, and high-speed motor/gear controllers. LDC sensors can be used in many different markets, including automotive, white goods, consumer electronics, mobile devices, computing, industrial, and medical.

The new sensing devices are implemented using the new family of LDC1000 devices. They are available in a 16-pin, 4-mm by 5-mm SON package. LDC technology enables sub-micron resolution in position-sensing applications with 16-bit resonance impedance and 24-bit inductance values. It Allows the sensor to be located remotely from the electronics, where PCBs cannot be placed, and consumes less than 8.5 mW during standard operation and less than 1.25 mW in standby mode.

Surprising new tests are possible
Surprising new tests are possible

“LDCs provide system designers with a new platform for developing breakthrough solutions to difficult system problems,” said Dave Heacock, senior vice president of TI Silicon Valley Analog. “LDCs provide high-resolution sensing of any metal or conductor – including the human body. We can’t wait to see what the engineers will come up with.”

Tools and support

The LDC1000EVM, which includes an MSP430F5528 microcontroller (MCU), is available to evaluate the device and can be purchased today. System designers can create a custom sensor coil and configure the LDC in seconds with TI’s new WEBENCH® Inductive Sensing Designer. The online tool simplifies the sensor coil design process and provides configuration settings for the LDC based on the coil’s characteristics, application requirements and system performance needs.

The optimized design can be easily exported to CAD programs, to quickly incorporate the sensor coil into the overall system design. Support is available on the Inductive Sensing Forum in the TI E2ETM Community, where engineers can ask questions and get answers from TI experts.

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