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AD7685:  16-Bit, 250 kSPS PulSAR® ADC in MSOP/QFN

Product Details


The AD7685 is a 16-bit, charge redistribution successive approximation, analog-to-digital converter (ADC) that operates from a single power supply, VDD, between 2.3 V to 5.5 V. It contains a low power, high speed, 16-bit sampling ADC with no missing codes, an internal conversion clock, and a versatile serial interface port. The part also contains a low noise, wide bandwidth, short aperture delay, track-and-hold circuit. On the CNV rising edge, it samples an analog input IN+ between 0 V to REF with respect to a ground sense IN−. The reference voltage, REF, is applied externally and can be set up to the supply voltage.

Power dissipation 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 or 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.

The AD7685 is housed in a 10-lead MSOP or a 10-lead QFN (LFCSP) with operation specified from −40°C to +85°C.

Applications

  • Battery-powered equipment
  • Medical instruments
  • Mobile communications
  • Personal digital assistants (PDAs)
  • Data acquisition
  • Instrumentation
  • Process controls

FEATURES and BENEFITS

  • 16-bit resolution with no missing codes
  • Throughput: 250 kSPS
  • INL: ±0.6 LSB typical, ±2 LSB maximum (±0.003% of FSR)
  • SINAD: 93.5 dB @ 20 kHz
  • THD: −110 dB @ 20 kHz
  • Pseudo differential analog input range 0 V to VREF with VREF up to VDD
  • No pipeline delay
  • Single-supply operation 2.3 V to 5.5 V with 1.8 V to 5 V logic interface
  • Serial interface SPI®-/QSPI™-/MICROWIRE™-/DSP-compatible
  • Daisy-chain multiple ADCs, BUSY indicator
  • Power dissipation
    1.4 μW @ 2.5 V/100 SPS
    1.35 mW @ 2.5 V/100 kSPS, 4 mW @ 5 V/100 kSPS
  • Standby current: 1 nA

Functional Block Diagram for AD7685

Of Note ...

For additional ADI Healthcare Products and related information, please visit www.analog.com/healthcare.

Technical Articles:

Documentation

Title Content Type File Type
AD7685: 16-Bit, 250 kSPS PulSAR ADC in MSOP Data Sheet (Rev D, 07/2014) (pdf, 634 kB) Data Sheets PDF
Tested ADC Driver to PulSAR ADC Application Notes HTML
AN-1141: Powering a Dual Supply Precision ADC with Switching Regulators  (pdf, 640 kB) Application Notes PDF
AN-931: Understanding PulSAR ADC Support Circuitry  (pdf, 299 kB)
This application note discusses in general the pitfalls that occur regularly when using SAR ADCs and, more importantly, how to easily prevent them.
Application Notes PDF
AN-932: Power Supply Sequencing  (pdf, 95 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-0213:Complete High Speed, High CMRR Precision Analog Front End for Process Control  (pdf, 288 kB) Circuit Note PDF
CN-0194: Galvanically Isolated, 2-Channel, 16-Bit, Simultaneous Sampling, Daisy-Chained Data Acquisition System  (pdf, 464 kB) Circuit Note PDF
CN-0130: Integrated Device Power Supply (DPS) for ATE with Output Voltage Range 0 V to 25 V  (pdf, 231 kB) Circuit Note PDF
CN-0104: Parametric Measurement Unit and Supporting Components for ATE Applications Using the AD5522 PMU and the AD7685 16-Bit ADC  (pdf, 247 kB) 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
UG-682: 6-Lead SOT-23 ADC Driver for the 8-/10-Lead Family of 14-/16-/18-Bit PulSAR ADC Evaluation Boards  (pdf, 433 kB) User Guides PDF
UG-340: Evaluation Board for the 10-Lead Family 14-/16-/18-Bit PulSAR ADCs  (pdf, 4636 kB) User Guides PDF
Voltage Reference Design for Precision Successive-Approximation ADCs
(Analog Dialogue, Volume 47 – June 2013)
Analog Dialogue HTML
High Speed Op Amp Drives a 16-Bit, 1-MSPS Differential-Input A/D Converter
(Analog Dialogue, Vol. 36, No. 6, November/December 2002)
Analog Dialogue HTML
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
Low-Power Data Conversion Technology Enhances Portability
(Electropages, 10/5/2006)
Product Reviews HTML
Lowest-Power 16-Bit ADC Optimizes Portable Designs
(eeProductCenter, 10/4/2006)
Product Reviews 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
8- to 18-Bit SAR ADCs ... From the Leader in High Performance Analog  (pdf, 1885 kB)
8- to 18-Bit SAR ADCs with Sample Rates up to 3 MSPS -- The latest additions to ADI’s ADC portfolio offer unrivaled functionality in terms of channel count and power supply voltage, optimal power/speed ratios, and the smallest packages to meet the demands of any data acquisition application, including portable, industrial, medical, wireless, and communications.
Overview PDF
Medical Applications Overview HTML
High Speed, High Accuracy 14-Bit, 16-Bit, and 18-Bit PulSAR ADCs  (pdf, 3826 kB)
A PulSAR Family Brochure (6/2006)
Overview PDF
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Evaluation Kits & Symbols & Footprints

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Companion Products

Suggested Companion Products


Recommended Driver Amplifiers for the AD7685 Recommended External Voltage Reference for the AD7685
  • For high precision, low power, small package, we recommend the ADR391 (2.5V) reference.
  • For low noise, high accuracy, low power, we recommend the ADR435 or the ADR4550 family of voltage references.
  • For a reference buffer, we suggest the AD8031 or the AD8605.

Recommended Digital Isolators for the AD7685
  • 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 Voltage Regulators for the AD7685
  • For low dropout regulators with inputs up to 5V, we recommend the low noise ADP151 or the low power ADP160.
  • For high current switching regulators with inputs up to 5V, we recommend the low noise ADP2114.
Recommended Power Solutions
  • For selecting voltage regulator products, use ADIsimPower.

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Price, packaging, availability

AD7685 Model Options
Model Package Pins Temp.
Range
Packing,
Qty
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
AD7685ACPZRL Status: Last Time Buy 10 ld LFCSP (3x3mm) 10 Ind Reel, 5000 - $6.58 Y  Material Info PDN Purchase
AD7685ACPZRL7 Status: Production 10 ld LFCSP (3x3mm) 10 Ind Reel, 1500 - $6.58 Y  Material Info Notify Me Purchase Sample
AD7685ARMZ Status: Production 10 ld MSOP 10 Ind Tube, 50 $7.28 $6.58 Y  Material Info PCN Purchase Sample
AD7685ARMZRL7 Status: Production 10 ld MSOP 10 Ind Reel, 1000 - $6.58 Y  Material Info PCN Purchase
AD7685BCPZRL Status: Last Time Buy 10 ld LFCSP (3x3mm) 10 Ind Reel, 5000 - $8.10 Y  Material Info PDN Purchase
AD7685BCPZRL7 Status: Production 10 ld LFCSP (3x3mm) 10 Ind Reel, 1500 - $8.10 Y  Material Info Notify Me Purchase Sample
AD7685BRMZ Status: Production 10 ld MSOP 10 Ind Tube, 50 $8.96 $8.10 Y  Material Info PCN Purchase Sample
AD7685BRMZRL7 Status: Production 10 ld MSOP 10 Ind Reel, 1000 - $8.10 Y  Material Info PCN Purchase
AD7685CCPZRL Status: Production 10 ld LFCSP (3x3mm) 10 Ind Reel, 5000 - $9.72 Y  Material Info Notify Me Purchase
AD7685CCPZRL7 Status: Production 10 ld LFCSP (3x3mm) 10 Ind Reel, 1500 - $9.72 Y  Material Info Notify Me Purchase Sample
AD7685CRMZ Status: Production 10 ld MSOP 10 Ind Tube, 50 $10.75 $9.72 Y  Material Info PCN Purchase Sample
AD7685CRMZRL7 Status: Production 10 ld MSOP 10 Ind Reel, 1000 - $9.72 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.

AD7685 Evaluation Kit
Model Description Price RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
EVAL-AD7685-PMDZ Status: Production Evaluation Board PMOD compatible form factor $27.00 Yes -
EVAL-AD7685SDZ Status: Production Evaluation Board SDP Interface $99.00 Yes -
EVAL-SDP-CB1Z Status: Production Evaluation Controller Board SDP $99.00 Yes -
SDP-PMD-IB1Z Status: Production Evaluation Interposer Board PMOD to SDP w/ Power Supply $55.00 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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