The industry's first differential inductive switch

12th May 2016

Nat Bowers

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Datasheet

Featuring a dual-coil architecture that automatically compensates for variations in temperature and component ageing, Texas Instruments has introduced what it claims to be the industry's first differential inductive switch. The LDC0851 detects the presence or absence of conductive material by using a simple coil drawn on a PCB.

This unique approach enables low-cost, highly reliable switching implementations for a variety of uses including buttons, knobs, door open/close detection and speed and directional sensing in personal electronics, appliances, industrial equipment and communications applications.

The LDC0851 provides a temperature-stable switching accuracy of better than 1% of the sensor coil diameter (up to 10 times more accurate than magnetic sensor-based designs), removing the need for production calibration and minimising part-to-part variation. The differential architecture maintains the switching threshold across variations in temperature, humidity and other environmental factors, as well as providing immunity to component ageing for stable, long-term performance.

Unlike alternative sensing technologies, the LDC0851's contactless and magnet-free design is immune nonconductive contaminants such as oil, dirt, dust or other environmental factors, providing designers a reliable, low-cost solution. The solution is also unaffected by DC magnetic fields, ensuring robust operation and reliability in a wide range of environments.

Duty cycling of the LDC0851 allows for less than 20µA average current consumption at 10 samples per second, which is up to five times lower than competitive solutions.

The LDC0851EVM evaluation module helps designers easily configure the LDC0851 and start designing it into a system without programming. The LDC0851EVM is available now in the TI store and through authorised distributors for $20.

An incremental rotary encoder reference design (TIDA-00828) demonstrates the LDC0851 in a simple 32-position rotary-knob design. Using only two LDC0851 inductive switches, the system can track rotation position and direction, and designers can easily scale the number of encoder positions up or down.

System designers can start their inductive-sensing design in minutes with TI's WEBENCH Coil Designer. This online tool simplifies sensor-coil design based on application and system requirements. The optimised design is exportable to a variety of CAD programmes to quickly incorporate the sensor coil into an overall system layout.

The eight-pin LDC0851 is available now in a 2x2mm WSON package from the TI store and authorised distributors, priced at $0.38 each in 1,000 unit quantities.