Automotive & Transportation

Differential Inductive Switch Debuts

23 May 2016

Texas Instruments (TI) introduced what it calls the industry's first differential inductive switch. The LDC0851 detects the presence or absence of conductive material using a simple coil drawn on a printed circuit board (PCB). This 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.

Texas Instruments' LDC0851 inductively detects the presence or  absence of conductive material, providing contactless, magnet-free switching  immune to dirt, dust, or stray magnetic fields. Image source: Texas  InstrumentsTexas Instruments' LDC0851 inductively detects the presence or absence of conductive material, providing contactless, magnet-free switching immune to dirt, dust, or stray magnetic fields. Image source: Texas InstrumentsThe LDC0851 provides a temperature-stable switching accuracy of better than one percent of the sensor coil diameter, removing the need for production calibration and minimizing part-to-part variation. Unlike alternative sensing technologies, the LDC0851's contactless and magnet-free design is immune to dirt, dust or other environmental factors, providing designers a reliable, low-cost solution. The device joins TI's existing portfolio of inductive-sensing integrated circuits (ICs) including the LDC1614 family of multichannel inductance-to-digital converters.

The LDC0851's differential architecture maintains the switching threshold across variations in temperature, humidity and other environmental factors, as well as providing immunity to component aging for stable, long-term performance. The solution is also unaffected by direct current (DC) magnetic fields, ensuring robust operation and reliability in a wide range of environments.

Duty cycling of the LDC0851 holds average current consumption below 20 µA while acquiring readings at 10 samples per second.

Tools and support to jump-start design

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 authorized distributors for $20 USD.

An incremental rotary encoder reference design (TIDA-00828) demonstrates the LDC0851 in a simple 32-position rotary-knob design. Using 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.

TI's WEBENCH Coil Designer online tool simplifies sensor-coil design based on application and system requirements. The optimized design is exportable

to a variety of computer-aided design (CAD) programs to quickly incorporate the sensor coil into an overall system layout.

Package, availability and pricing

The eight-pin LDC0851 is available now in a 2 mm x 2 mm very-thin small-outline no-lead (WSON) package from the TI store and authorized distributors. Unit pricing is $0.38 in 1,000-piece quantities.



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