Touch Sensor Makes Direct and Simpler Control of Products

With the smart phone, people have become more reliant on touch/proximity means for the control of electronic equipment nowadays. Touch sensing technology helps to enhance the performance of electronic products or automotive devices and is increasingly popular. Now we are going to find out the touch/proximity sensing solutions proposed by ON Semiconductor in the upgrade of product performance.

Noise Rejection Mechanism and Superior Sensitivity Solutions for Automobile and Industrial Environment

Touch/proximity sensing technology is increasingly popular for electronic hardware in line with the expansion of the market size for electronics. The convenient and simple mode of control is widely receptive to the market and is indeed a point of promotion. The consumer electronics market has enjoyed the fastest growth over the years, among other markets of electronic products, but other areas of applications are also on stable growth including the automotive and industrial use.

It is estimated that the market size of capacitance-sensor will amount to USD 31.79 billion by 2022. By then, the annual shipment volume of the product will be 21.14 billion pieces (according to the statistical analysis of Markets & Markets). Application of touch sensors to the automotive and industrial market just constituted part of these figures, but has been determined as a vital force driving the growth of this area of application (including touch switch, touch pad and touch screen).

Professional touch sensor solution for automotive or industrial application varied significantly from application to portable devices (smart phone) or home appliances. The former needs to address the existence of electromagnetic interference (EMI). The existence of EMI in automotive or industrial equipment is inevitable, which may be emitted from the motor, cable & wire harness, A/C coil, and other power driving auxiliary devices and equipment. The rejection of noise is critical for providing highly reliable touch sensing mechanism for enhancing user experience. The robustness of the device ensures sustainable reliability of the touch sensing performance in extreme environment (exposure to anticipated pulse, vibration, and high temperature).

In driving energy efficient innovations, ON Semiconductor has recently introduced a new touch/proximity sensing solution, the LC717A30UJ high dynamic range capacitance-to-digital converter, which combines industry-leading performance, cost-effectiveness and convenience in a single chip. Developed with the objective of enhancing the performance of capacitive touch sensors, the LC717A30UJ integrates new and innovative capacitance cancellation and noise rejection mechanisms to combat the effects of electromagnetic interference (EMI), improving on competing solutions in terms of its sensitivity. It can detect changes in capacitance down to femtofarad (fF) levels. 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, enhancing users’ control options to address a wide range of application scenarios.

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 (ON/OFF) based on the system application needs. The LC717A30UJ 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 in the field.

The high level of sensitivity of LC717A30UJ enables gesture motions as well as offering conventional touch functionality. It is capable of operating with multiple layers of gloves or air gap between the sensor/PCB and the protective cover. As a result, engineers can eliminate the inclusion of a light guide from the assembly and reduce overall complexity and production costs. In summary, it provides engineers with a single chip touch/proximity sensing solution that is easy to implement and extremely cost effective. To support the needs of automotive application such as vehicle entry systems and dashboard controls, the device is AEC-Q100 compliant.

The LC717A30UJ delivers rapid responsiveness, with a measurement time of 16 milliseconds (ms) for its 8 sensing channels and runs off a +2.6 volt (V) to +5.5 V supply with a low-power standby mode of 0.1 µA. The high degree of integration means that minimal external components are required, further reducing the bill of materials. 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, automobiles, industrial equipment, and lighting controls.

ON Semiconductor makes available the LC717A30UJGEVK capacitance touch sensor operation evaluation boards for clients to evaluate the operation of various switch patterns. Developers interested in this product may access further information for the quick development of products.

By: ON Semiconductor