Inductive-capacitive resonator at heart of touch solution

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.

TI’s LDC2114 and LDC2112 solutions are 1.8V, multi-channel low-noise inductance-to-digital converters 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 1MHz to 30MHz.

With adjustable sensitivity per input channel, the LDC2112 and LDC2114 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 multi-level buttons.

The LDC2112 and LDC2114 devices can operate in an ultra-low-power mode of 6µA 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 400Hz I²C, and the only external components necessary for operation are supply bypass capacitors and a COM pin capacitor to ground.

The LDC2112 and LDC2114 devices are ideal for smartphones, wearable devices, tablets and PCs, virtual reality headsets, remote controls, and human-machine interface (HMI) panels and keypads.

The LDC2112 and LDC2114 are supported by the LDC2114EVM evaluation module. The LDC2114EVM can connect up to four buttons using the LDCCOILEVM or customized coils designed using the WEBENCH Inductive Sensing Designer. The board offers integrated and configurable algorithms for button press detection with onboard LED indicators.