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AD7785:  3-Channel, Low Noise, Low Power, 20-Bit Σ-Δ ADC with On-Chip In-Amp and Reference

The AD7785 is a low power, low noise, complete analog front ends for high precision measurement applications. It contains a low noise 20-bit Σ-Δ ADC with three differential analog inputs. The on-chip, low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 40 nV when the update rate equals 4.17 ...More

AD7785:  3-Channel, Low Noise, Low Power, 20-Bit Σ-Δ ADC with On-Chip In-Amp and Reference

Product Description

The AD7785 is a low power, low noise, complete analog front ends for high precision measurement applications. It contains a low noise 20-bit Σ-Δ ADC with three differential analog inputs. The on-chip, low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 40 nV when the update rate equals 4.17 Hz.

The device contains a precision low noise, low drift internal band gap reference and can also accept an external differential reference. Other on-chip features include programmable excitation current sources, burnout currents, and a bias voltage generator, the bias voltage generator being used to set the common-mode voltage of a channel to AVDD/2.

The device can be operated with either the internal clock or an external clock. The output data rate from the part is software-programmable and can be varied from 4.17 Hz to 470 Hz.

The part operates with a power supply from 2.7 V to 5.25 V. It consumes a current of 400 µA typical and is housed in 16-lead TSSOP packages.

Applications

  • Thermocouple measurements
  • RTD measurements
  • Thermistor measurements
  • Gas analysis
  • Industrial process control
  • Instrumentation
  • Portable instrumentation
  • Blood analysis
  • Smart transmitters
  • Liquid/gas chromatography
  • 6-digit DVM

    • RESOURCES & TOOLS

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    • Up to 20 bits effective resolution
    • RMS noise
      40 nV @ 4.17 Hz
      85 nV @ 16.7 Hz
    • Current: 400 µA typ
    • Power-down: 1 µA max
    • Low noise programmable gain instrumentation amp
    • Band gap reference with 4 ppm/°C drift typ
    • Update rate: 4.17 Hz to 470 Hz
    • 3 differential inputs
    • Simultaneous 50 Hz/60 Hz rejection
    • Resolution (Bits): 20bit
    • T-Put Rate: 470SPS
    • # Chan: 3
    • Supply V: Single(+2.7 to +5.25)
    • Pwr Diss: 2.5mW
    • Interface: Ser,SPI
    • Ain Range: ± (Vref/Gain)
    • SNR (dB): n/a
    • Pkg Type: SOP

    Functional Block Diagram for AD7785

    OF NOTE ...

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    Part# Bits Throughput Rate # of Inputs Operating Pwr Diss
    AD7785 20 470SPS 3 2.5mW
    AD7792 16 470SPS 3 2.5mW
    AD7798 16 470SPS 3 2mW
    AD7799 24 470SPS 3 2.5mW
    AD7793 24 470SPS 3 2.5mW
    AD7795 16 470SPS 6 2.5mW
    AD7466 12 200KSPS 1 900µW
    AD7879 12 105KSPS 6 2.3mW
    AD7794 24 470SPS 6 2.5mW
    AD7889 12 105KSPS 6 2.3mW
    AD7467 10 200KSPS 1 630µW
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    Pricing, Packaging & Availability

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    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
    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.

    Production Availability
    This is the date Analog Devices, Inc. anticipates that the product will ship from the warehouse. Most orders ship within 48 hours of this date.Once an order has been placed, Analog Devices, Inc. will send an Order Acknowledgement email to confirm your delivery date. It is important to note the scheduled dock date on the order entry screen. We do take orders for items that are not in stock, so delivery may be scheduled at a future date. Also, please note the warehouse location for the product ordered. We have warehouses in the United States, Europe and Southeast Asia. Transit times from these sites may vary.
    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.

    View PCN
    This is the list of Product Change Notifications (PCN) published on the web for this model. Click on the link to access PCN Information.Only select pre-2009 PCN�s are available on-line. To obtain a pre-2009 PCN, contact your ADI Sales Rep. For more information on ADI's PCN process, please visit our PCN Policy Statement 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 into your cart to check sample availability.