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AD7794:  6-Channel, Low Noise, Low Power, 24-Bit Sigma Delta ADC with On-Chip In-Amp and Reference

Product Details


The AD7794/AD7795 are low power, low noise, complete analog front ends for high precision measurement applications. They contain a low noise, 24-/16-bit Σ-Δ ADC with six differential inputs. The on-chip low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC.

Each device contains a precision, low noise, low drift internal band gap reference, and can also accept up to two external differential references. Other on-chip features include programmable excitation current sources, burnout currents, and a bias voltage generator that is used to set the common-mode voltage of a channel to AVDD/2. The low-side power switch can be used to power down bridge sensors between conversions, minimizing the system’s power consumption. The AD7794/AD7795 can operate with either an internal clock or an external clock. The output data rate from each part can vary from 4.17 Hz to 470 Hz.

Both parts operate with a power supply from 2.7 V to 5.25 V. The B-grade parts (AD7794 and AD7795) are specified for a temperature range of −40°C to +105°C while the C-grade part (AD7794) is specified for a temperature range of −40°C to +125°C. They consume a current of 400 μA typical and are housed in a 24-lead TSSOP.

Applications

  • Temperature measurement
  • Pressure measurement
  • Weigh scales
  • Strain gage transducers
  • Gas analysis

FEATURES and BENEFITS

  • Chinese data sheet available
  • Up to 23 effective bits
  • RMS noise: 40 nV @ 4.17 Hz, 85 nV @ 16.7 Hz
  • Current: 400 μA typical
  • Power-down: 1 μA maximum
  • Low noise, programmable gain, instrumentation amp
  • Band gap reference with 4 ppm/°C drift typical
  • Update rate: 4.17 Hz to 470 Hz
  • Six differential analog inputs
  • Internal clock oscillator
  • Simultaneous 50 Hz/60 Hz rejection
  • Reference detect
  • Programmable current sources

Functional Block Diagram for AD7794

Documentation

Title Content Type File Type
AD7794/AD7795: 6-Channel, Low Noise, Low Power, 24-/16-Bit Sigma Delta ADC with On-Chip In-Amp and Reference Data Sheet (Rev D, 03/2007) (pdf, 807 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
Delta-Sigma Rocks RF, As ADC Designers Jump On Jitter
(Electronic Design, 1/12/06)
Technical Articles HTML
Sigma Delta ADCs (< 15 kSPS) Product Selection Guide HTML
Healthcare ICs
Healthcare ICs Solutions Bulletin, Volume 11, Issue 2
Solutions Bulletins HTML
ICs for Programmable Logic Control and Distributed Control Systems  (pdf, 976 kB)
Analog Devices leadership in industrial IC technology, with the development of the iCMOS™ and iPolar™ processes, has uniquely defined high voltage and low voltage integration to deliver smaller, higher performance, and more cost effective ICs for industrial systems.
Overview PDF
FAQs for the AD779x family. FAQs/RAQs 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.

Product Recommendations & Reference Designs

Companion Products

Suggested Companion Products


Recommended High Accuracy, Precision References - 2.5V for the AD7794

  • For applications requiring the lowest noise performance and and low power output trim adjust, we recommend the ADR441.
  • For high output current applications, we recommend the ADR431.
  • For wide supply applications, we recommend the AD780.
Recommended Digital Isolators for the AD7794
  • For process control applications, we recommend the ADuM1400 and the ADuM1200 icoupler.
  • For isolated USB designs in healthcare and industrial control, we recommend the ADuM4160.
Recommended Power Solutions

  • For selecting voltage regulator products, use ADIsimPower.

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Price, packaging, availability

AD7794 Model Options
Model Package Pins Temp.
Range
Packing,
Qty
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
AD7794BRU Status: Production 24 ld TSSOP 24 Ind Tube, 62 $7.97 $6.78 N  Material Info PCN Purchase
AD7794BRU-REEL Status: Last Time Buy 24 ld TSSOP 24 Ind Reel, 2500 - $6.78 N  Material Info PCN/PDN Purchase
AD7794BRUZ Status: Production 24 ld TSSOP 24 Ind Tube, 62 $6.90 $5.87 Y  Material Info PCN Purchase Sample
AD7794BRUZ-REEL Status: Production 24 ld TSSOP 24 Ind Reel, 2500 - $5.87 Y  Material Info PCN Purchase
AD7794CRUZ Status: Production 24 ld TSSOP 24 Ind Tube, 62 $7.46 $6.38 Y  Material Info PCN Purchase
AD7794CRUZ-REEL Status: Production 24 ld TSSOP 24 Ind Reel, 2500 - $6.38 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.

AD7794 Evaluation Board
Model Description Price RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
EVAL-AD7794EBZ 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.

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