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AD7731:  Low Noise, High Throughput 24-Bit Sigma-Delta ADC

Product Details


The AD7731 is a complete analog front-end for process control applications. The device has a proprietary programmable gain front end that allows it to accept a range of input signal ranges, including low level signals, directly from a transducer. The sigmadelta architecture of the part consists of an analog modulator and a low pass programmable digital filter, allowing adjustment of filter cutoff, output rate and settling time.

The part features three buffered differential programmable gain analog inputs (which can be configured as five pseudo-differential inputs), as well as a differential reference input. The part operates from a single +5 V supply and accepts seven unipolar analog input ranges: 0 to +20 mV, +40 mV, +80 mV, +160 mV, +320 mV, +640 mV and +1.28 V, and seven bipolar ranges: ±20 mV, ±40 mV, ±80 mV, ±160 mV, ±320 mV, ±640 mV and ±1.28 V. The peak-to-peak resolution achievable directly from the part is 16 bits at an 800 Hz output rate. The part can switch between channels with 1 ms settling time and maintain a performance level of 13 bits of peak-to-peak resolution.

The serial interface on the part can be configured for three-wire operation and is compatible with microcontrollers and digital signal processors. The AD7731 contains self-calibration and system calibration options and features an offset drift of less than 5 nV/°C and a gain drift of less than 2 ppm/°C.

The part is available in a 24-lead plastic DIP, a 24-lead SOIC and 24-lead TSSOP package.

Applications

  • Process Control
  • PLCs/DCS
  • Industrial Instrumentation

FEATURES and BENEFITS

  • 24-Bit Sigma-Delta ADC
  • 16 Bits p-p Resolution at 800 Hz Output Rate
  • Programmable Output Rates up to 6.4 kHz
  • Programmable Gain Front End
  • ±0.0015% Nonlinearity
  • Buffered Differential Inputs
  • Programmable Filter Cutoffs
  • FASTStep™* Mode for Channel Sequencing
  • Single Supply Operation

* FASTStep is a trademark of Analog Devices, Inc.

Functional Block Diagram for AD7731

Documentation

Title Content Type File Type
AD7731: Low Noise, High Throughput 24-Bit Sigma-Delta ADC Data Sheet  (Rev A, 05/2009) (pdf, 411 kB) Data Sheets PDF
AN-311: How to Reliably Protect CMOS Circuits Against Power Supply Overvoltaging  (pdf, 217 kB) Application Notes PDF
AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-Delta ADC  (pdf, 222 kB) Application Notes PDF
AN-615: Peak-to-Peak Resolution Versus Effective Resolution  (pdf, 70 kB)
This application note describes effective resolution and peak-to-peak resolution and highlights the difference between these two specifications.
Application Notes PDF
AN-397: Electrically Induced Damage to Standard Linear Integrated Circuits:  (pdf, 149 kB)
The Most Common Causes and the Associated Fixes to Prevent Reoccurrence
Application Notes PDF
AN-202: An IC Amplifier User’s Guide to Decoupling, Grounding, and Making Things Go Right for a Change  (pdf, 76 kB) Application Notes PDF
AN-389: Using Sigma-Delta Converters-Part 2  (pdf, 590 kB)
When to Use/How to Use Sigma-Delta ADCs; Continuation of Part 1 Discussion.
Application Notes PDF
AN-388: Using Sigma-Delta Converters-Part 1  (pdf, 590 kB)
When to Use/How to Use Sigma-Delta ADCs
Application Notes PDF
AN-283: Sigma-Delta ADCs and DACs  (pdf, 1699 kB)
Overview of Sigma-Delta Concepts: Oversampling, Noise Shaping Using the Sigma-Delta Modulator, Digital Filtering and Decimation.
Application Notes PDF
MS-2210: Designing Power Supplies for High Speed ADC  (pdf, 327 kB) Technical Articles PDF
Delta-Sigma Rocks RF, As ADC Designers Jump On Jitter
(Electronic Design, 1/12/06)
Technical Articles HTML
Designing and Applying Remote Field Instruments
by Albert O' Grady and Jim Ryan, Analog Devices B.V.
...Good things can come in small packages because of on-chip capabilities
(Control Engineering, September 1998)
Technical Articles HTML
Circuit Suggestions Using Features and Functionality of New Sigma-Delta ADCs Technical Articles HTML
Ask the Applications Engineer-27: What problems am I most likely to run into when instrumenting an industrial system?
(Analog Dialogue, Vol. 33, No. 2, February, 1999)
Analog Dialogue HTML
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
Sigma-Delta ADC Tutorial
An interactive illustration showing the behavior of an idealized sigma-delta A/D converter.
Utilities and Conversions HTML
Sigma Delta Register Configuration Assistant
Easily program the configuration registers for the sigma delta ADCs. Use pull-down menus to determine the correct hex values to load into the registers, and generate pseudo-code.
Design Calculators HTML
Digital Filter Model Spreadsheets
These spreadsheet tools show the response of the digital filter section of the AD71xx and AD77xx devices based on input parameters.
Design Calculators HTML
AD7731 Code Examples Code Examples HTML

Evaluation Kits & Symbols & Footprints

Evaluation Boards & KitsView the Evaluation Boards and Kits page for documentation and purchasing

Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.

SampleSample & Buy

Price, packaging, availability

AD7731 Model Options
Model Package Pins Temp.
Range
Packing,
Qty
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
AD7731BNZ Status: Production 24 ld PDIP 24 Ind Tube, 15 $12.45 $10.59 Y  Material Info PCN Purchase Sample
AD7731BR Status: Production 24 ld SOIC - Wide 24 Ind Tube, 31 $13.56 $11.53 N  Material Info PCN Purchase
AD7731BR-REEL Status: Last Time Buy 24 ld SOIC - Wide 24 Ind Reel, 1000 - $11.53 N  Material Info PCN/PDN Purchase
AD7731BR-REEL7 Status: Production 24 ld SOIC - Wide 24 Ind Reel, 400 - $11.53 N  Material Info PCN Purchase
AD7731BRU Status: Production 24 ld TSSOP 24 Ind Tube, 62 $13.56 $11.53 N  Material Info PCN Purchase
AD7731BRU-REEL Status: Last Time Buy 24 ld TSSOP 24 Ind Reel, 2500 - - N  Material Info PCN/PDN Contact ADI
AD7731BRU-REEL7 Status: Production 24 ld TSSOP 24 Ind Reel, 1000 - $11.53 N  Material Info PCN Purchase
AD7731BRUZ Status: Production 24 ld TSSOP 24 Ind Tube, 62 $12.09 $10.28 Y  Material Info PCN Purchase Sample
AD7731BRUZ-REEL Status: Last Time Buy 24 ld TSSOP 24 Ind Reel, 2500 - $10.28 Y  Material Info PCN/PDN Purchase
AD7731BRUZ-REEL7 Status: Production 24 ld TSSOP 24 Ind Reel, 1000 - $10.28 Y  Material Info PCN Purchase
AD7731BRZ Status: Production 24 ld SOIC - Wide 24 Comm. Tube, 31 $12.69 $10.79 Y  Material Info PCN Purchase Sample
AD7731BRZ-REEL Status: Production 24 ld SOIC - Wide 24 Comm. Reel, 1000 - $10.79 Y  Material Info PCN Purchase
AD7731BRZ-REEL7 Status: Production 24 ld SOIC - Wide 24 Comm. Reel, 400 - $10.79 Y  Material Info PCN Purchase
Price Table Help

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.

AD7731 Evaluation Kit
Model Description Price RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
EVAL-AD7731EBZ Status: Last Time Buy Evaluation Board - Yes - Contact ADI

Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.

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