Add to Signal Chain Designer

AD7785:  3-Channel, Low Noise, Low Power, 20-Bit Σ-Δ ADC with On-Chip In-Amp and Reference

Product Details


The AD7785 is a low power, low noise, complete analog front ends for high precision measurement applications. It contains a low noise 20-bit Σ-Δ ADC with three differential analog inputs. The on-chip, low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 40 nV when the update rate equals 4.17 Hz.

The device contains a precision low noise, low drift internal band gap reference and can also accept an external differential reference. Other on-chip features include programmable excitation current sources, burnout currents, and a bias voltage generator, the bias voltage generator being used to set the common-mode voltage of a channel to AVDD/2.

The device can be operated with either the internal clock or an external clock. The output data rate from the part is software-programmable and can be varied from 4.17 Hz to 470 Hz.

The part operates with a power supply from 2.7 V to 5.25 V. It consumes a current of 400 µA typical and is housed in 16-lead TSSOP packages.

Applications

  • Thermocouple measurements
  • RTD measurements
  • Thermistor measurements
  • Gas analysis
  • Industrial process control
  • Instrumentation
  • Portable instrumentation
  • Blood analysis
  • Smart transmitters
  • Liquid/gas chromatography
  • 6-digit DVM

FEATURES and BENEFITS

  • Up to 20 bits effective resolution
  • RMS noise
    40 nV @ 4.17 Hz
    85 nV @ 16.7 Hz
  • Current: 400 µA typ
  • Power-down: 1 µA max
  • Low noise programmable gain instrumentation amp
  • Band gap reference with 4 ppm/°C drift typ
  • Update rate: 4.17 Hz to 470 Hz
  • 3 differential inputs
  • Simultaneous 50 Hz/60 Hz rejection

Functional Block Diagram for AD7785

Documentation

Title Content Type File Type
AD7785: 3-Channel, Low Noise, Low Power, 20-Bit Σ-Δ ADC with On-Chip In-Amp and Reference Data Sheet (Rev 0, 04/2007) (pdf, 629 kB) Data Sheets PDF
AN-968: Current Sources: Options and Circuits  (pdf, 131 kB) Application Notes PDF
AN-311: How to Reliably Protect CMOS Circuits Against Power Supply Overvoltaging  (pdf, 217 kB) Application Notes PDF
AN-880: ADC Requirements for Temperature Measurement Systems  (pdf, 423 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-101: Cross Plot Generator Allows Quick A/D Converter Evaluation  (pdf, 280 kB) 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-347: Shielding and Guarding  (pdf, 688 kB)
How to Exclude Interference-Type Noise. What to do and Why to do it-A Rational Approach
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
High-resolution ADCs — an overview
The dramatic reduction in the cost of high-resolution ADCs brings a number of benefits to designers.
(Electronic Products, 4/23/2010)
Technical Articles HTML
Sigma Delta ADCs (< 15 kSPS) Product Selection Guide 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
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

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

AD7785 Model Options
Model Package Pins Temp.
Range
Packing,
Qty
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
AD7785BRUZ Status: Production 16 ld TSSOP 16 Ind Tube, 96 $5.01 $4.25 Y  Material Info PCN Purchase Sample
AD7785BRUZ-REEL Status: Production 16 ld TSSOP 16 Ind Reel, 2500 - $4.25 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.

AD7785 Evaluation Board
Model Description Price RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
EVAL-AD7785EBZ Status: Production Evaluation Board $59.00 Yes -

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.

Check Inventory & Purchase

View Sales and Distribution Offices

沪ICP备09046653号
content here.
content here.

Review this Product

Close