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AD7738:  8-Channel, 8.5 kHz, 24-Bit Sigma-Delta A/D Converter

Product Details


The AD7738 is a high precision, high throughput analog front end. True 16-bit peak-to-peak resolution is achievable with a total conversion time of 117 µs (8.5 kHz channel switching) making it ideally suitable for high resolution multiplexing applications.

The AD7738 is based on a sigma-delta architecture and features up to 24 bits of no missing codes performance. The part can be configured via a simple digital interface, which allows users to balance the noise performance against data throughput up to a 15.4 kHz conversion rate. The analog front end features 8 single-ended or 4 fully differential input channels with unipolar or bipolar 625 mV, 1.25 V and 2.5V input ranges and accepts a common mode input voltage from 200 mV above AGND to AVDD-300 mV. The multiplexer output is pinned out externally allowing the user to implement programmable gain or signal conditioning before applying the input signal to the ADC. The differential reference input features “No Reference” detect capability. The ADC also supports per channel system calibration options.

The digital serial interface can be configured for three-wire operation and is compatible with microcontrollers and digital signal processors. All interface inputs are Schmitt triggered.

The part is specified for operation over the extended industrial temperature range of -40ºC to +105ºC and is available in 28-lead TSSOP package.

FEATURES and BENEFITS

  • High resolution ADC
    - 24 bits no missing codes
    - ±0.0015% Nonlinearity
  • Optimized for Fast Channel Switching
    - 18-Bits p-p Resolution (21 Bits Effective) at 500 Hz
    - 16-Bits p-p Resolution (19 Bits Effective) at 8.5 kHz
    - 15-Bits p-p Resolution (18 Bits Effective) at 15 kHz
    - On-Chip Per Channel System Calibration
  • Configurable Inputs
    - 8 Single-Ended or 4 Fully Differential
  • Input Ranges
    - +625 mV, +1.25 V, +2.5 V, ±625 mV, ±1.25 V, ±2.5 V
  • 3-Wire Serial Interface
    - SPI®, QSPI™, MICROWIRE™ and DSP Compatible
    - Schmitt Trigger on Logic Inputs
  • Single-Supply Operation
    - 5 V Analog Supply
    - 3 V or 5 V Digital Supply
  • Package: 28-Lead TSSOP

Functional Block Diagram for AD7738

Documentation

Title Content Type File Type
AD7738: 8-Channel, High Throughput, 24-Bit Sigma-Delta A/D Converter Data Sheet (Rev 0, 11/2002) (pdf, 407 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
AN-664: AD7732/AD7734/AD7738/AD7739 in Low Power Applications  (pdf, 131 kB)
This application note refers only to the AD7739, but is also generally applicable to the AD7732,AD7734 and AD7738. The purpose of this application note is to explain how to optimize the use of these parts in power sensitive applications.
Application Notes PDF
AN-626: Using the AD7732/AD7734/AD7738/AD7739 Checksum Register  (pdf, 106 kB) Application Notes PDF
AN-663: AD7732/AD7734/AD7738/AD7739 Calibration Registers  (pdf, 96 kB)
This application note concentrates on the AD7739 but is also applicable to the AD7732,AD7734,and AD7738. The purpose of this application note is to explore the calibration registers in more detail than is found on the data sheets.
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
ChipCenter Review: Analog Front End Family Provides Input Channel Options For Precision Measurement Applications  (htm)
... When you think of Sigma-Delta analog-to-digital converters you probably think of precision but not speed.
Technical Articles HTM
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
Analog Front End Family Provides Input Channel Options For Precision Measurement Applications  (htm)
(Analog Avenue Product Review)
Product Reviews HTM
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
AD7732/34/38/39 Codeword Tool
A tool to calculate codewords from voltages in the AD7732/34/38/39 Sigma-Delta ADCs.
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

AD7738 Model Options
Model Package Pins Temp.
Range
Packing,
Qty
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
AD7738BRU Status: Production 28 ld TSSOP 28 Ind Tube, 50 $10.68 $9.08 N  Material Info PCN Purchase
AD7738BRU-REEL7 Status: Last Time Buy 28 ld TSSOP 28 Ind Reel, 1000 - $9.08 N  Material Info PCN/PDN Purchase
AD7738BRUZ Status: Production 28 ld TSSOP 28 Ind Tube, 50 $9.25 $7.86 Y  Material Info PCN Purchase Sample
AD7738BRUZ-REEL Status: Last Time Buy 28 ld TSSOP 28 Ind Reel, 2500 - $7.86 Y  Material Info PCN/PDN Purchase
AD7738BRUZ-REEL7 Status: Production 28 ld TSSOP 28 Ind Reel, 1000 - $7.86 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.

AD7738 Evaluation Kit
Model Description Price RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
EVAL-AD7738EBZ 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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