Texas Instruments LDC2114 Evaluation Module inductive touch sensing

The Texas Instruments LDC2114 Evaluation Module inductive touch sensing detects and measures the presence of conductive objects to implement inductive touch buttons. The product features a multichannel low-noise inductance-to-digital converter optimised for inductive touch applications on monolithic surfaces.

Inductive sensing technology enables touch button design on a wide variety of materials such as metal, glass, plastic and wood by measuring small deflections of conductive targets. The sensor for an inductive touch system is a coil that can be implemented on a small, compact PCB located behind a panel and protected from the environment.

The product can connect up to four buttons using the LDCCOILEVM or customised coils designed using the WEBENCH inductive sensing designer. The board offers integrated and configurable algorithms for button press detection with onboard LED indicators. The product consumes as little as 6 µA at 0.625 samples per second, and designers can configure the device at different duty cycles to optimise the power consumption of their system.

The product is a 1.8 V, multichannel, low-noise, inductance-to-digital converter with integrated algorithms to implement inductive touch applications. The two-channel LDC2112 and four-channel LDC2114 devices employ an innovative inductive-capacitive (LC) resonator that offers high rejection of noise and interference, with a wide range of oscillation frequencies from 1 to 30 MHz. With adjustable sensitivity per input channel, the product can reliably detect material deflections of less than 200 nm with a wide range of physical button structures and materials. The high-resolution measurement further enables the implementation of multilevel buttons.

The devices can operate in an ultralow-power mode of 6 µA for optimal battery life or can be toggled into a higher scan rate for more responsive button press detection for game play or other low-latency applications. The devices are configured through 400 Hz I2C, and the only external components necessary for operation are supply bypass capacitors and a COM pin capacitor to ground.