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AD7725:  16-Bit Sigma Delta ADC with a Programmable Post Processor

Product Status:Production
Data
Sheet
AD7725 Data Sheet Rev A, 02/2004 (pdf 442kB)

Product Details

Product Status:Production
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The AD7725 is a complete 16-bit, sigma-delta analog to digital converter with on chip user-programmable signal conditioning. The output of the modulator is processed by three cascaded finite impulse response (FIR) filters, followed by a user-programmable post processor. The user has complete control over the filter response, the filter coefficients and the decimation ratio.

The AD7725 is specified for input bandwidths up to 300 kHz and an output word rate of 600 kHz maximum. The input sample rate is set either by the crystal oscillator or an external clock, , which has a specified value of 9.6MHz and a maximum value of 14.4MHz. The CLKIN frequency directly determines the maximum input bandwidth of the device with the relationship being BW (max) = CLKIN/32. The conversion data is available via a serial or parallel interface.

To program the Post Processor, either the on-chip, default filter or a user-defined filter in the form of a configuration file can be loaded into the device. The user-defined filter can be loaded from a DSP or an external EPROM with a serial interface or from a DSP with a parallel interface.

The user-defined filter configuration file can be generated using a digital filter design package called 'Filter Wizard'. This package allows the user to design different filter types and generates the appropriate configuration file to be loaded to the device.

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FEATURES and BENEFITS

  • Programmable Filtering
    - Any Characteristic up to 108 Tap FIR and/or IIR
  • Polynomial Signal Conditioning up to 8th Order
  • Flexible Programming Modes
    - Boot from DSP or External EPROM
    - Parallel/Serial Interface
  • Internal Default Filter for Evaluation
  • Programmable Decimation and Output Word Rate
  • 14.4 MHz Max Master Clock Frequency
  • 0 V to +4 V (Single-Ended) or ±2 V (Differential) Input Range
  • Power Supplies: AVDD, DVDD: 5 V ± 5%
  • On-Chip 2.5 V Voltage Reference
  • 44-Lead MQFP Package

Functional Block Diagram for AD7725

AD7725 Diagram

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Of Note ...

Visit an overview of the AD7725 Development Tools for extended information on this new Programmable Sigma-Delta Converter!

Documentation

Title Content Type File Type
AD7725: 16-Bit 900 kSPS Sigma-Delta ADC with Programmable Post Processor Data Sheet  (Rev A, 02/2004) (pdf, 442 kB) Data Sheets PDF
AN-311: How to Reliably Protect CMOS Circuits Against Power Supply Overvoltaging  (pdf, 217 kB) Application Notes PDF
AN-282: Fundamentals of Sampled Data Systems  (pdf, 2131 kB) Application Notes PDF
AN-342: Analog Signal-Handling for High Speed and Accuracy.  (pdf, 468 kB)
Signal handling techniques for optimizing DAC and ADC performance. 		Application Notes PDF
AN-280: Mixed Signal Circuit Technologies  (pdf, 2101 kB)
Considers problems which arise when reality (& Murphy) intervene in a design which otherwise seems satisfactory in terms of theory and modeling. 		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
Analog Devices AD7725 16-Bit Delta-Sigma ADC  (htm)
... Analog Devices' New 16-Bit Sigma Delta ADC Features On-Chip Programmable Post Processor -- Post processor runs 130 million multiply-accumulate operations per second to free up external processing requirements. (ChipCenter Product Review, Product of the Week) 		Technical Articles HTM
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
A/D Converter Mantra: Customize
(EE Times Product Review, 1/9/2003) 		Product Reviews 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

Evaluation Kits & Symbols & Footprints

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