Semtech SX9500 Capacitive Proximity / Button Sensor is a low-power four-channel capacitive controller that operates as a proximity or button sensor. SX9500 includes sophisticated on-chip auto-calibration circuitry to regularly perform sensitivity adjustments. This auto-calibration feature allows SX9500 to maintain peak performance over a wide variation of temperature, humidity, and noise environments. SX9500 operates directly from a 2.7 to 5.5V input supply voltage. This Semtech sensor includes a separate I²C serial bus supply input to enable communication with 1.8-5.5V hosts. The I²C serial communication bus reports proximity or touch detection and facilitates adjustments to parameter settings. Upon a proximity detection, the NIRQ output asserts, enabling the user to determine the relative proximity distance or obtain an indication of detection. A dedicated transmit enable (TXEN) pin is available to synchronize capacitive measurements for applications that require synchronous detection. The TXEN pin enables low supply current and high noise immunity by only measuring proximity when requested.