Ultra-Low Power, 1-Channel, Capacitance
Converter for Proximity Sensing
AD7151
FEATURES
GENERAL DESCRIPTION
Ultra-low power
2.7 V to 3.6 V, 70 μA
Response time: 10 ms
Adaptive environmental compensation
1 capacitance input channel
Sensor capacitance (CSENS) 0 pF up to 13 pF
Sensitivity to 1 fF
EMC tested
2 modes of operation
Standalone with fixed settings
Interfaced to a microcontroller for user-defined settings
Proximity detection output flag
2-wire serial interface (I2C compatible)
Operating temperature
−40°C to +85°C
10-lead MSOP package
The AD7151 delivers a complete signal processing solution for
capacitive proximity sensors, featuring an ultra-low power
converter with fast response time. The AD7150 is a 2-channel
alternative to the AD7151.
The AD7151 uses 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 AD7151 operates in standalone mode using the
fixed power-up settings and indicates detection on a digital
output. Alternatively, the AD7151 can be interfaced to a
microcontroller 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.
APPLICATIONS
Proximity sensing
Contactless switching
Position detection
Level detection
The AD7151 operates with a 2.7 V to 3.6 V power supply. It is
specified over the temperature range of −40°C to +85°C.
FUNCTIONAL BLOCK DIAGRAM
VDD
AD7151
CSENS
EXC
Σ-Δ CDC
EXCITATION
DIGITAL
FILTER
THRESHOLD
GND
SERIAL
INTERFACE
SCL
SDA
OUT
07086-001
CIN
Figure 1.
Rev. 0
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