AD7797:  Low Power 24-Bit Sigma-Delta A/D Converter for Bridge Sensors

The AD7797 is a complete analog front end for high precision bridge sensor applications such as weighscales. The AD7797 contains a ∑-∆ ADC capable of 24-bit resolution. The on-chip instrumentation ...More

AD7797:  Low Power 24-Bit Sigma-Delta A/D Converter for Bridge Sensors

Product Description

The AD7797 is a complete analog front end for high precision bridge sensor applications such as weighscales. The AD7797 contains a ∑-∆ ADC capable of 24-bit resolution. The on-chip instrumentation amplifier has a fixed gain of 128 so signals of small amplitude such as those from bridge sensors can be interfaced directly to the ADC.

The part has one differential input. The device also contains a temperature sensor which is internally connected to the ADC. This temperature sensor can be used to perform temperature compensation of the bridge.

The device can be operated with the internal clock, or alternatively, an external clock can be used. The output data rate from the parts is software-programmable and can be varied from 4.17 Hz to 123 Hz.

The part operates with a power supply from 2.7 V to 5.25 V. It consumes a current of 250 µA typical and is housed in a 16-lead TSSOP package.

Applications

  • Weighscales
  • Strain Gauges
  • Industrial Process Control
  • Instrumentation
  • Portable instrumentation
  • Features

    • RMS Noise: 65 nV
    • Instrumentation amp
    • Temperature Sensor
    • Internal clock oscillator
    • Simultaneous 50 Hz/60 Hz rejection
    • Update rate: 4.17 Hz to 123 Hz
    • Current: 250 µA typ
    • Power-down: 1 µA
    • Power supply: 2.7 V to 5.25 V
    • –40°C to +85°C temperature range
    • Independent interface power supply
    • 16-lead TSSOP package

    Diagrams

    AD7797 Diagram
    Functional Block Diagram for AD7797

    Specifications

    Resolution (Bits) 24bit
    T-Put Rate 123SPS
    # Chan 1
    Supply V Single(+2.7 to +5.25) ,Single(+2.7),Single(+3),Single(+3.3),Single(+5)
    Pwr Diss (max) 1.6mW
    Interface Ser,SPI
    Ain Range ± (Vref/128)
    SNR (dB) n/a
    Pkg Type SOP

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    Part# Res Throughput Rate # of Inputs Operating Pwr Diss
    AD7797 24 123SPS 1 1.6mW
    AD7796 16 123SPS 1 1.6mW
    AD7766 24 128KSPS 1 18mW
    AD7767 24 128KSPS 1 18mW
    AD9874 24 541.5KSPS 1 79.5mW
    AD7791 24 120SPS 1 800µW
    AD7764 24 312KSPS 1 371mW
    AD7765 24 156KSPS 1 371mW
    AD7763 24 625KSPS 1 956mW
    AD7760 24 2.5MSPS 1 958mW
    AD7762 24 625KSPS 1 958mW
    Pricing, Packaging & Availability

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    Model
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    • Pre-Release: The model has not been released to general production, but samples may be available.
    • Production: The model is currently being produced, and generally available for purchase and sampling.
    • Last Time Buy: The model has been scheduled for obsolescence, but may still be purchased for a limited time.
    • Obsolete: The specific part is obsolete and no longer available. Other models listed in the table may still be available (if they have a status that is not obsolete).
    Package Description
    The package for this IC (i.e. DIP, SOIC, BGA). An Evaluation Board is a board engineered to show the performance of the model, the part is included on the board.

    For detailed drawings and chemical composition please consult our  Package Site

    Pin Count
    Pin Count is the number of pins, balls, or pads on the device. Pin-out diagrams & pin function descriptions may be found in the datasheet.

    Temperature Range
    This is the acceptable operating range of the device. The various ranges specified are as follows:
    • Commercial: 0 to +70 degrees Celsius
    • Military : -55 to +125 degrees Celsius
    • Industrial: Temperature ranges may vary by model. Please consult the datasheet for more information.
    • Automotive: -40 to +125 degrees Celsius
    Price
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    Production Availability
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    Sample availability may be better than production availability. Please enter samples into your cart to check sample availability.

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    Due to environmental concerns, ADI offers many of our products in lead-free versions. For more information about lead-free parts, please consult our Pb (Lead) free information page.

    *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.
    **Sample availability may be better than production availability. Please enter samples iinto your cart to check sample availability.

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