GENERAL DESCRIPTION
The AD7156 delivers a complete signal processing solution for capacitive sensors, featuring an ultralow power converter with fast response time.
The AD7156 uses an Analog Devices, Inc., capacitance-to digital converter (CDC) technology, which combines features important for interfacing to real sensors, such as high input sensitivity and high tolerance of both input parasitic ground capacitance and leakage current.
The integrated adaptive threshold algorithm compensates for any variations in the sensor capacitance due to environmental factors like humidity and temperature or due to changes in the
dielectric material over time. 

FEATURES
Ultralow power
  Power supply voltage: 1.8 V to 3.6 V
  Operation power supply current: 70 μA typical
  Power-down current: 2 μA typical
Fast response time
  Conversion time: 10 ms per channel
  Wake-up time from serial interface: 300 μs
Adaptive environmental compensation
2 capacitance input channels
  Sensor capacitance (CSENS): 0 pF up to 13 pF
  Sensitivity up to 3 fF
2 modes of operation
  Standalone with fixed settings
  Interfaced to a microcontroller for user-defined settings
2 detection output flags
2-wire serial interface (I2C-compatible)
Operating temperature: −40°C to +85°C
10-lead LFCSP package (3 mm × 3 mm × 0.8 mm)

APPLICATIONS
Buttons and switches
Proximity sensing
Contactless switching
Position detection
Level detection
Portable products