TI adds differential mode to inductive-sensing
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, 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 with a reliable, low-cost solution. It is an addition to the company’s inductive-sensing ICs including the LDC1614 family of multichannel inductance-to-digital converters.
Low power: Duty cycling of the LDC0851 allows for less than 20-µA average current consumption at 10 samples per second, which is up to five times lower than competitive solutions.
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 ageing 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 direct current (DC) magnetic fields, ensuring robust operation and reliability in a wide range of environments.
An evaluation module, LDC0851EVM, at $20, helps designers configure the LDC0851 and start designing it into a system without programming.
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 scale the number of encoder positions up or down. Other inductive-sensing reference designs are available in the TI Designs reference design library.
Also available is TI’s WEBENCH Coil Designer, an online tool that 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.
The eight-pin LDC0851, in a 2 x 2-mm very-thin small-outline no-lead (WSON) package, is priced at $0.38 (1,000).