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