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AD7985:  16-Bit, 2.5 MSPS PulSAR 11 mW ADC in QFN

Product Details

The AD7985 is a 16-bit, 2.5 MSPS successive approximation analog-to-digital converter (SAR ADC). It contains a low power, high speed, 16-bit sampling ADC, an internal conversion clock, an internal reference (and buffer), error correction circuits, and a versatile serial interface port. On the rising edge of CNV, the AD7985 samples an analog input, IN+, between 0 V and REF with respect to a ground sense, IN−. The AD7985 features a very high sampling rate turbo mode (TURBO is high) and a reduced power normal mode (TURBO is low) for low power applications where the power is scaled with the throughput.

In normal mode (TURBO is low), 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 provide an optional busy indicator. It is compatible with 1.8 V, 2.5 V, and 2.7 V supplies using the separate VIO supply.

The AD7985 is available in a 20-lead LFCSP with operation specified from −40°C to +85°C.


  • Battery-powered equipment
  • Communications
  • ATE
  • Data acquisition systems
  • Medical Instruments


  • 16-bit resolution with no missing codes
  • Throughput: 2.5 MSPS (TURBO high), 2.0 MSPS (TURBO low)
  • Low power dissipation
       15.5 mW at 2.5 MSPS, with external reference
       28 mW at 2.5 MSPS, with internal reference
  • INL: ±0.7 LSB typical, ±1.5 LSB maximum
  • SNR
       88.5 dB, with on-chip reference
       90 dB, with external reference
  • 4.096 V internal reference: typical drift of ±10 ppm/°C
  • Pseudo differential analog input voltage range
       0 V to VREF with VREF up to 5.0 V
       Allows use of any input range
  • Please see data sheet for additional features

AD7985 Functional Block Diagram

Similar Products

  • AD7988-1: Single Channel; 16-Bit; 100 kSPS; 700uW Ultra Low Power PulSAR ADC in Small MSOP & QFN(3mm*3mm)
  • AD7988-5: Single Channel; 16-Bit; 500 kSPS; 3.5W Ultra Low Power PulSAR ADC in Small MSOP & QFN(3mm*3mm)
  • AD7980: Single Channel;16-Bit; 1 MSPS;Low Power PulSAR ADC in Small MSOP & QFN(3mm*3mm)
  • AD7983: Single Channel;16-Bit; 1.33 MSPS PulSAR ADC in Small MSOP & QFN(3mm*3mm)
  • AD7982: Single Channel;18-Bit; 1 MSPS PulSAR 7.0 mW ADC in Small MSOP & QFN(3mm*3mm)
  • AD7984: Single Channel;18-Bit; 1.33 MSPS PulSAR 10.5 mW ADC in Small MSOP & QFN(3mm*3mm)
  • AD7986: Single Channel;18-Bit; 2 MSPS; Low Power 15 mW; Differential Input; PulSAR ADC in 4mm*4mm QFN

Of Note ...

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Title Content Type File Type
AD7985: 16-Bit, 2.5 MSPS, PulSAR 15.5 mW ADC in LFCSP Data Sheet (Rev B, 07/2014) (pdf, 656 kB) Data Sheets PDF
AN-1141: Powering a Dual Supply Precision ADC with Switching Regulators  (pdf, 640 kB) Application Notes PDF
AN-877: Interfacing to High Speed ADCs via SPI  (pdf, 1594 kB) Application Notes PDF
AN-935: Designing an ADC Transformer-Coupled Front End  (pdf, 363 kB) Application Notes PDF
AN-742: Frequency Domain Response of Switched-Capacitor ADCs  (pdf, 401 kB) Application Notes PDF
CN-0260: Oversampled SAR ADC with PGA Achieving Greater Than 125 dB Dynamic Range  (pdf) Circuit Note PDF
The Data Conversion Handbook Design Handbooks HTML
MT-031: Grounding Data Converters and Solving the Mystery of  (pdf, 144 kB) Tutorials PDF
MT-002: What the Nyquist Criterion Means to Your Sampled Data System Design  (pdf, 152 kB) Tutorials PDF
MT-001: Taking the Mystery out of the Infamous Formula, "SNR=6.02N + 1.76dB," and Why You Should Care  (pdf, 94 kB) Tutorials PDF
MS-2689: Isolating SPI for High Bandwidth Sensors  (pdf, 577 kB) Technical Articles PDF
Front-End Amplifier and RC Filter Design for a Precision SAR Analog-to-Digital Converter Technical Articles HTML
MS-2210: Designing Power Supplies for High Speed ADC  (pdf, 327 kB) Technical Articles PDF
MS-2022: Seven Steps to Successful Analog-to-Digital Signal Conversion (Noise Calculation for Proper Signal Conditioning)  (pdf, 277 kB) Technical Articles PDF
MS-2124: Understanding AC Behaviors of High Speed ADCs  (pdf, 276 kB) Technical Articles PDF
Nine Often Overlooked ADC Specifications  (pdf, 445 kB)
Analog-to-digital converters (ADCs) have many specifications; some are more important for a given application than others. Understanding these specifications and controlling external devices affecting the ADC will lead to better performance.
Technical Articles PDF
Voltage Reference Design for Precision Successive-Approximation ADCs
(Analog Dialogue, Volume 47 – June 2013)
Analog Dialogue HTML
SAR ADC & Driver Quick-Match Guide  (pdf, 251 kB)
Find drivers for ADI's most popular single-ended and differential SAR ADCs based on your specific application conditions.
Product Selection Guide PDF
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

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Companion Products

Suggested Companion Products

Recommended Driver Amplifiers for the AD7985

Recommended External Voltage References for the AD7985
  • For a low noise, high accuracy 2.5V reference, we recommend the ADR431 or the ADR4525.
  • For a low noise, high accuracy 3V reference, we suggest the ADR433 or the ADR4533.
  • For a low noise, high accuracy 5V reference, we recommend the ADR435 or the ADR4550.
  • For driving the voltage reference input, we recommend the AD8031 or the AD8605 buffer amplifiers.

Recommended Digital Isolators for the AD7985
  • For SPI Interface, lowest power, 2.5 kVrms isolation, we recommend the ADuM1401.
  • For SPI Interface, enhanced system-level ESD performance, 2.5 kVrms isolation, we recommend the ADuM3401.
  • For SPI Interface, low power, 5.0 kVrms isolation, we recommend the ADuM4401.
  • For SPI Interface, smallest package, low voltage I/O (1.8 V to 5.5 V), we recommend the ADuM3481.
Recommended Power Solutions
  • For selecting voltage regulator products, use ADIsimPower.

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Price, packaging, availability

AD7985 Model Options
Model Package Pins Temp.
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
AD7985BCPZ Status: Production 20 ld LFCSP (4x4mm) 20 Ind Tray, 490 $21.76 $18.50 Y  Material Info PCN Purchase Sample
AD7985BCPZ-RL7 Status: Production 20 ld LFCSP (4x4mm) 20 Ind Reel, 1500 - $18.50 Y  Material Info PCN Purchase
Price Table Help

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.

AD7985 Evaluation Board
Model Description Price RoHS View PCN/ PDN Check Inventory/
EVAL-AD7985EBZ Status: Production Evaluation Board $59.00 Yes -
EVAL-CED1Z Status: Production Evaluation Board $249.00 Yes -

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.

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