ON Semiconductor has introduced a highly integrated capacitance-to-digital converter IC that looks to speed up the implementation and reduce the component count of electrostatic capacitance touch sensor applications. The LC717A00AR, which is the first in a series of ON Semiconductor touch sensor integrated circuits, simplifies the replacement of mechanical switches with capacitive touch sensors for applications including home appliances, audio/visual equipment, computer peripherals and automotive instrument panels.
Featuring eight capacitor sensing inputs and eight digital outputs, it uses a proprietary differential capacitance detection technology to enable high sensitivity and high noise resistance. A built-in logic circuit detects the ON/OFF state of each input and outputs the appropriate result without the need for any additional components or control software. Capacitances in the femto Farad order can be detected and touch sensitivity is pre-configured, eliminating the need for complicated sensitivity adjustments.
“Because of its high sensitivity, the LC717A00AR issuitable for applications where users may wear gloves or where an air gap or a thick, protective glass cover is needed such as washing machines, refrigerators and cooking appliances,” said Takekiyo Okumura, general manager, of ON Semiconductor’s SANYO division. “In addition to integrated anti-noise circuitry, the device automatically compensates for changes in temperature and humidity to prevent false touch detection and operational failure from environmental changes.
As well as operating as a standalone device, the device allows parameters to be modified using an external microcontroller via a built-in serial interface that can be configured for I2C or SPI operation. The device is compatible with a supply voltage of 2.6 volts (V) to 5.5V and operates with a typical current consumption of 320 micro-amps (µA) at a supply voltage of 2.8 V. Rated operating temperature is -40°C to 105°C.