The LC717A30UJ uses mutual capacitance to detect changes in capacitance down to femtofarad (fF) levels. Parasitic capacitance cancellation raises the detector sensitivity, while its built-in noise rejection mechanism combats the effects of electromagnetic interference (EMI). Eight capacitance-sensing input channels make the LC717A30UJ highly optimized for use in systems where an array of switches is required. The device includes an integrated multiplexer for input channel selection, A/D converter, a dual-stage amplifier that determines capacitance changes plus outputs analogue amplitude values, system clock, power-on reset circuit, and related control logic. Both I2C and SPI interfaces are selectable based on the application needs.
As the device’s sensitivity has a range of 150 millimeters (mm) - beyond the scope of any competing device on the market – its higher sensitivity enables gesture motions as well as offering conventional touch functionality, thereby enhancing users’ control options to address a wide range of application scenarios. In addition, it can operate with an airgap between the sensor/PCB and the protective cover - so engineers can eliminate the inclusion of a light guide from the assembly and reduce overall complexity. This device also includes an integrated automatic calibration function which optimizes and self-calibrates total capacitance according to electrode, line capacitance, and surrounding environment, thus significantly accelerating system development cycle time as well as robustness.