Ultralow Power, 1.8 V, 3 mm × 3 mm,
2-Channel Capacitance Converter
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)
Buttons and switches
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.
By default, the AD7156 operates in standalone mode using the
fixed power-up settings and indicates detection on two digital
outputs. Alternatively, the AD7156 can be interfaced to a micro-
controller via the serial interface, the internal registers can be
programmed with user-defined settings, and the data and status
can be read from the part.
The AD7156 operates with a 1.8 V to 3.6 V power supply. It is
specified over the temperature range of −40°C to +85°C.
FUNCTIONAL BLOCK DIAGRAM
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
©2008 Analog Devices, Inc. All rights reserved.