LC717A30UJ capacitance-to-digital converter. Source: ON Semiconductor. ON Semiconductor has introduced a touch/proximity sensing solution that combines high performance, cost-effectiveness and convenience in a single chip. The LC717A30UJ high dynamic range 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 millimeters (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 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 that 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 in the field.
The LC717A30UJ provides a measurement time of 16 milliseconds (ms) for its eight sensing channels and runs off a +2.6 volt (V) to +5.5 V supply with a low-power standby mode of one microampere (µA). To support the needs of automotive applications, such as vehicle entry systems and dashboard controls, the device is AEC-Q100 compliant. With its high integration level and wide dynamic range, it can also be employed in a range of touch or gesture human interfaces in industrial and consumer end products such as induction cookers, refrigerators, home entertainment systems, building automation equipment, industrial equipment and lighting controls.
The LC717A30UJ comes in an SSOP-30 package and is priced at $1.05 per unit in 10,000 unit quantities. The LC717A30UJGEVK capacitance touch sensor operation evaluation boards are available to evaluate the operation of various switch patterns.
