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AD7747:  24-BIT CAPACITANCE-TO-DIGITAL CONVERTER WITH TEMPERATURE SENSOR

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 ...More

AD7747:  24-BIT CAPACITANCE-TO-DIGITAL CONVERTER WITH TEMPERATURE SENSOR

Product Description

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 programmable 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.

Applications

Automotive, industrial, and medical systems for:

  • Pressure measurement
  • Position sensing
  • Proximity sensing
  • Level sensing
  • Flowmeters
  • Impurity detections

RESOURCES & TOOLS

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  • 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
  • Resolution (Bits): 24bit
  • T-Put Rate: 45.5SPS
  • # Chan: 1
  • Supply V: Single(+2.7 to +5.25)
  • Pwr Diss: 4.25mW
  • Sleep Pwr Diss: 10µW
  • Ain Range: ± 8 pF (Delta C) ,(2Vref) p-p
  • Ref Int/Ext: Int/Ext
  • Product Description: 24-bit, Cap-to-Dig Conv w/1 SE/Diff Capacitive Input Ch for interface to Single Electrode Cap Sensor

Functional Block Diagram for AD7747

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Pin Count
Pin Count is the number of pins, balls, or pads on the device. Pin-out diagrams & pin function descriptions may be found in the datasheet.

Temperature Range
This is the acceptable operating range of the device. The various ranges specified are as follows:
  • Commercial: 0 to +70 degrees Celsius
  • Military : -55 to +125 degrees Celsius
  • Industrial: Temperature ranges may vary by model. Please consult the datasheet for more information.
  • Automotive: -40 to +125 degrees Celsius
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*The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
**Sample availability may be better than production availability. Please enter samples into your cart to check sample availability.