The LC717A30UJ capacitance-to-digital converter 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). The 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, analog-to-digital converter, dual-stage amplifier that determines capacitance changes plus outputs analog amplitude values, system clock, power-on reset circuit, and all the necessary control logic to create a total solution. Both I2C and SPI interfaces are selectable based on the system application needs.
As the device’s sensitivity has a range of 150 mm, 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 is capable of operating with an airgap between the sensor/PCB and the protective cover. This device also includes an integrated automatic calibration function, which optimizes and self-calibrates total capacitance according to electrode, line capacitance, and surrounding environment.
The LC717A30UJ is offered in a SSOP-30 package and priced at $1.05 each/10,000 unit quantities. A datasheet is available at http://www.onsemi.com/PowerSolutions/product.do?id=LC717A30UJ