AD7731:  CMOS, Low Noise 24-Bit Sigma-Delta ADC with Fast Channel-Channel Settling Time

The AD7731 is a complete analog front-end for process control applications. The device has a proprietary programmable gain front end that allows it to accept a range of input signal ranges, including ...More

AD7731:  CMOS, Low Noise 24-Bit Sigma-Delta ADC with Fast Channel-Channel Settling Time

Product Description

The AD7731 is a complete analog front-end for process control applications. The device has a proprietary programmable gain front end that allows it to accept a range of input signal ranges, including low level signals, directly from a transducer. The sigma-delta architecture of the part consists of an analog modulator and a low pass programmable digital filter, allowing adjustment of filter cutoff, output rate and settling time.

The part features three buffered differential programmable gain analog inputs (which can be configured as five pseudo-differential inputs), as well as a differential reference input. The part operates from a single +5 V supply and accepts seven unipolar analog input ranges: 0 to +20 mV, +40 mV, +80 mV, +160 mV, +320 mV, +640 mV and +1.28 V, and seven bipolar ranges: ±20 mV, ±40 mV, ±80 mV, ±160 mV, ±320 mV, ±640 mV and ±1.28 V. The peak-to-peak resolution achievable directly from the part is 16 bits at an 800 Hz output rate. The part can switch between channels with 1 ms settling time and maintain a performance level of 13 bits of peak-to-peak resolution.

The serial interface on the part can be configured for three-wire operation and is compatible with microcontrollers and digital signal processors. The AD7731 contains self-calibration and system calibration options and features an offset drift of less than 5 nV/°C and a gain drift of less than 2 ppm/°C.

The part is available in a 24-lead plastic DIP, a 24-lead SOIC and 24-lead TSSOP package.

Features

  • 24-Bit Sigma-Delta ADC
  • 16 Bits p-p Resolution at 800 Hz Output Rate
  • Programmable Output Rates up to 6.4 kHz
  • Programmable Gain Front End
  • ±0.0015% Nonlinearity
  • Buffered Differential Inputs
  • Programmable Filter Cutoffs
  • FASTStep™ Mode for Channel
    Sequencing
  • Single Supply Operation

Diagrams

AD7731 Diagram
Functional Block Diagram for AD7731

Specifications

Resolution (Bits) 24bit
T-Put Rate 6.4kSPS
# Chan 3
Supply V Single(+5)
Pwr Diss (max) 67.5mW
Interface Ser,SPI
Ain Range (2Vref/PGA Gain) p-p,(Vref/PGA Gain) p-p
SNR (dB) 125dB
Pkg Type DIP,SOIC,SOP

AD7356 - Differential Input, Dual, Simultaneous Sampling, 5 MSPS, 12-Bit, SAR ADC

AD7401A - Isolated Sigma-Delta Modulator

AD7352 - Differential Input, Dual, Simultaneous Sampling, 3 MSPS, 12-Bit, SAR ADC

AD7949 - 14-Bit, 8-Channel, 250 kSPS PulSAR® ADC

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Part# Res Throughput Rate # of Inputs Operating Pwr Diss
AD7731 24 6.4KSPS 3 67.5mW
AD7767 24 128KSPS 1 18mW
AD7766 24 128KSPS 1 18mW
AD7793 24 470SPS 3 2.5mW
AD7799 24 470SPS 3 2.5mW
AD7713 24 205SPS 3 5.5mW
AD7690 18 400KSPS 1 20mW
AD7982 18 1MSPS 1 8.6mW
AD7984 18 1.33MSPS 1 14mW
AD7678 18 100KSPS 1 26mW
AD7693 16 500KSPS 1 21.5mW
Pricing, Packaging & Availability

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Model
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Status
Status indicates the current lifecycle of the product. This can be one of 4 stages:
  • 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
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.

Available Ship Date
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.

RoHS Compliant
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.

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