AD7747 Converter Datasheet

AD7747 Datasheet PDF, Equivalent


Part Number

AD7747

Description

24-Bit Capacitance-to-Digital Converter

Manufacture

Analog Devices

Total Page 29 Pages
Datasheet
Download AD7747 Datasheet


AD7747
24-Bit Capacitance-to-Digital Converter
with Temperature Sensor
AD7747
FEATURES
GENERAL DESCRIPTION
Capacitance-to-digital converter
New standard in single chip solutions
Interfaces to single or differential grounded sensors
Resolution down to 20 aF (that is, up to 19.5-bit ENOB)
Accuracy: 10 fF
Linearity: 0.01%
Common-mode (not changing) capacitance up to 17 pF
Full-scale (changing) capacitance range ±8 pF
Update rate: 5 Hz to 45 Hz
Simultaneous 50 Hz and 60 Hz rejection at 8.1 Hz update
Active shield for shielding sensor connection
Temperature sensor on-chip
Resolution: 0.1°C, accuracy: ±2°C
Voltage input channel
Internal clock oscillator
2-wire serial interface (I2C® compatible)
Power
2.7 V to 5.25 V single-supply operation
0.7 mA current consumption
Operating temperature: −40°C to +125°C
16-lead TSSOP package
APPLICATIONS
Automotive, industrial, and medical systems for
Pressure measurement
Position sensing
Proximity sensing
Level sensing
Flow metering
Impurity detection
The AD7747 is a high-resolution, Σ-Δ capacitance-to-digital
converter (CDC). The capacitance to be measured is connected
directly to the device inputs. The architecture features inherent
high resolution (24-bit no missing codes, up to 19.5-bit effective
resolution), high linearity (±0.01%), and high accuracy (±10 fF
factory calibrated). The AD7747 capacitance input range is
±8 pF (changing), and it can accept up to 17 pF common-mode
capacitance (not changing), which can be balanced by a program-
mable on-chip digital-to-capacitance converter (CAPDAC).
The AD7747 is designed for single-ended or differential
capacitive sensors with one plate connected to ground. For
floating (not grounded) capacitive sensors, the AD7745 or
AD7746 are recommended.
The part has an on-chip temperature sensor with a resolution of
0.1°C and accuracy of ±2°C. The on-chip voltage reference and
the on-chip clock generator eliminate the need for any external
components in capacitive sensor applications. The part has a
standard voltage input that, together with the differential reference
input, allows easy interface to an external temperature sensor,
such as an RTD, thermistor, or diode.
The AD7747 has a 2-wire, I2C-compatible serial interface. The
part can operate with a single power supply of 2.7 V to 5.25 V.
It is specified over the automotive temperature range of
−40°C to +125°C and is housed in a 16-lead TSSOP package.
FUNCTIONAL BLOCK DIAGRAM
VDD
VIN(+)
TEMP
SENSOR
CLOCK
GENERATOR
AD7747
VIN(–)
CIN1(+)
CIN1(–)
SHLD
MUX
24-BIT Σ-Δ
GENERATOR
DIGITAL
FILTER
I2C
SERIAL
INTERFACE
EXCITATION
CAP DAC 1
CAP DAC 2
CONTROL LOGIC
CALIBRATION
VOLTAGE
REFERENCE
SDA
SCL
RDY
REFIN(+) REFIN(–)
Figure 1.
GND
Rev. 0
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.
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Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.

AD7747
AD7747* Product Page Quick Links
Last Content Update: 11/01/2016
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Reference Materials
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Design Resources
• AD7747 Material Declaration
• PCN-PDN Information
• Quality And Reliability
• Symbols and Footprints
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Features 24-Bit Capacitance-to-Digital Converter with Temperature Sensor AD7747 FEATURE S GENERAL DESCRIPTION Capacitance-to- digital converter New standard in singl e chip solutions Interfaces to single o r differential grounded sensors Resolut ion down to 20 aF (that is, up to 19.5- bit ENOB) Accuracy: 10 fF Linearity: 0. 01% Common-mode (not changing) capacita nce up to 17 pF Full-scale (changing) c apacitance range ±8 pF Update rate: 5 Hz to 45 Hz Simultaneous 50 Hz and 60 H z rejection at 8.1 Hz update Active shi eld for shielding sensor connection Tem perature sensor on-chip Resolution: 0.1 °C, accuracy: ±2°C Voltage input cha nnel Internal clock oscillator 2-wire s erial interface (I2C® compatible) Powe r 2.7 V to 5.25 V single-supply operati on 0.7 mA current consumption Operating temperature: −40°C to +125°C 16-le ad TSSOP package APPLICATIONS Automotiv e, industrial, and medical systems for Pressure measurement Position sensing P roximity sensing Level sensing Flow metering Impurity detection.
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