High Temperature, 16-Bit, 600 kSPS PulSAR ADC

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Product Details

The AD7981 is a 16-bit, successive approximation, PulSAR® analog-to-digital converter (ADC) designed for high temperature operation. The AD7981 is capable of sample rates of up to 600 kSPS while maintaining low power consumption from a single power supply, VDD. It is a fast throughput, high accuracy, high temperature,successive approximation register (SAR) ADC, packaged in a small form factor with a versatile serial port interface (SPI).

On the CNV rising edge, the AD7981 samples an analog input, IN+, between 0 V and REF with respect to a ground sense, IN−. The reference voltage, REF, is applied externally and can be set independent of the supply voltage, VDD. The device 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 supply, VIO.

For space constrained applications, the AD7981 is available in a 10-lead mini small outline package (MSOP) with operation specified from −55°C to +175°C and 10-lead ceramic flat package (FLATPACK) with operation specified from −55°C to +210°C. These packages are designed for robustness at extreme temperatures, including monometallic wire bonding, and are qualified for up to 1000 hours of operation at the maximum temperature rating.

The AD7981 is a member of a growing series of high temperature qualified products offered by Analog Devices, Inc. For a complete selection of available high temperature products, see the high temperature product list and qualification data available at


  • Downhole drilling and instrumentation
  • Avionics
  • Heavy industrial
  • High temperature environments

Product Lifecycle

icon-recommended Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kits


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EV-HT-200CDAQ1 Circuit Diagram

EV-HT-200CDAQ1 Photo

Product Details

EV-HT-200CDAQ1 builds on the CN0365 analog front end reference design from with the goal of providing a foundation for a high temperature, low power microcontroller-based data acquisition and control solution that meets the requirements for many downhole instrumentation and other high temperature applications. Based upon the AD7981 analog-to-digital SAR converter, this reference design demonstrates a full featured system with two high speed simultaneously sampled channels along with 8 additional multiplexed channels suitable for covering the acquisition requirements of a broad range of downhole tools (10 channels total). This analog front end is connected to the VORAGO Technologies VA10800 ARM® Cortex®-M0 based microcontroller via multiple SPI ports. Once acquired, the data can be processed locally or transmitted via a UART or optional RS485 communications interface. Other supporting components on the board, including memory, clock, power and passives are all rated for high temperature operation by their respective suppliers and verified to operate reliably at 200°C or higher. In addition to the hardware, open source firmware is supplied for the project using FreeRTOS with optimized drivers and data acqusition protocol with multiple modes of operation. Open source PC software included allows the users to connect to the board via UART to control acquisition modes, view data, log data and perform signal analysis. This platform is suitable for reference design, rapid prototyping (such as new sensor techniques) and lab testing of high temperature instrumentation systems.

Reference Designs


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CN0365 Circuit Diagram

CN0365 Photo

Design Resources

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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.

AD7981 Material Declaration
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Evaluation Boards Pricing displayed is based on 1-piece.
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.