Differential Inductive Switch Simplifies Design

Texas Instruments (TI) today introduced a differential inductive switch, with a dual-coil architecture that automatically compensates for variations in temperature and component aging. The LDC0851 detects the presence or absence of conductive material by using a simple coil drawn on a printed circuit board (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 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.

Key features and benefits of the LDC0851: Stable switching threshold: The 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. High accuracy: The device can deliver better than 1 percent switching accuracy, which is up to 10 times more accurate than magnetic sensor-based designs, reducing the need for production calibration.

High reliability: The device's immunity to nonconductive contaminants such as oil, dirt and dust can help extend product lifetimes and reduce replacement costs. The solution is also unaffected by dc magnetic fields, ensuring robust operation and reliability in a wide range of environments. Low power: Duty cycling of the LDC0851 allows for less than 20-uA 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 authorized distributors for US$20.

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