Features and Benefits

  • 18-bit resolution with no missing codes
  • Throughput: 250 kSPS
  • INL: ±0.75 LSB typical, ±1.5 LSB maximum (±6 ppm of FSR)
  • Dynamic range: 102 dB typical at 250 kSPS
  • Oversampled dynamic range: 125 dB at1 kSPS
  • Noise-free code resolution: 20 bits at 1 kSPS
  • Effective resolution: 22.7 bits at 1 kSPS
  • See data sheet for additional features
AD7691-EP supports defense and aerospace applications (AQEC standard)
  • Download AD7691-EP data sheet (pdf)
  • Military temperature range: –55°C to +105°C 
  • Controlled manufacturing baseline 
  • One assembly/test site 
  • One fabrication site 
  • Enhanced product change notification 
  • Qualification data available on request
  • V62/14632-01XE DSCC Drawing Number

Product Details

The AD7691 is an 18-bit, charge redistribution, successive approximation, analog-to-digital converter (ADC) that operates from a single power supply, VDD, between 2.3 V and 5 V. It contains a low power, high speed, 18-bit sampling ADC with no missing codes, an internal conversion clock, and a versatile serial interface port. On the CNV rising edge, it samples the voltage difference between the IN+ and IN− pins. The voltages on these pins usually swing in opposite phase between 0 V and REF. The reference voltage, REF, is applied externally and can be set up to the supply voltage. 

The part’s power scales linearly with throughput.

The SPI-compatible serial interface also features the ability, using the SDI input, to daisy-chain several ADCs on a single 3-wire bus and provides an optional busy indicator. It is compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate VIO supply.

The AD7691 is housed in a 10-lead MSOP or a 10-lead QFN (LFCSP) with operation specified from −40°C to +85°C.


  • Battery-powered equipment
  • Data acquisitions
  • Seismic data acquisition systems
  • Instrumentation
  • Medical instruments

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (2)

Documentation & Resources

  • View All (17)
  • Data Sheets (3)
  • Application Notes (2)
  • User Guides (2)
  • Tested Product Combinations (1)
  • Technical Books (1)
  • Tutorials (4)
  • Product Selection Guide (1)
  • Circuit Note (1)
  • Technical Articles (2)
  • Tools & Simulations

    Precision ADC Driver Tool

    The Precision ADC Driver Tool is a web application that simulates the performance of precision ADC and driver combinations. Potential issues with driver selection, kickback settling, and distortion are flagged, and design tradeoffs can be quickly evaluated. Simulations and calculations include system noise, distortion, and settling of the ADC input

    Precision ADC Driver Tool

    IBIS Models

    AD7685 IBIS Models

    Reference Designs (1)

    Product Recommendations

    AD7691 Companion Parts

    Recommended Digital Isolators

    • For SPI Interface, low power, 5.0 kVrms isolation: ADUM4401.
    • For SPI Interface, smallest package, low voltage I/O (1.8 V to 5.5 V): ADUM3481.
    • For SPI Interface, enhanced system-level ESD performance, 2.5 kVrms isolation: ADUM3401.
    • For SPI Interface, lowest power, 2.5 kVrms isolation: ADUM1401.

    Recommended External Voltage References

    • For low drift, low noise, low power: ADR4550.
    • For low drift, low noise and high current output applications: ADR435.
    • For driving the voltage reference input: AD8031, AD8655.
    • For low drift, low noise and low dropout: ADR445.

    Recommended Driver Amplifiers

    Design Resources

    ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

    PCN-PDN Information

    Sample & Buy

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    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.