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AD7685: 16-Bit, 250 kSPS PulSAR ADC in MSOP Data Sheet (Rev. D)4/1/2004PDF634 kB
Overview
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
- Daisy-chain multiple ADCs, BUSY indicator
- 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
- 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
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
Product Categories
Markets and Technologies
Product Lifecycle
Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (2)
Documentation & Resources
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AN-742: Frequency Domain Response of Switched-Capacitor ADCs (Rev. C)2/14/2015PDF427 K
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AN-931: Understanding PulSAR ADC Support Circuitry (Rev. 0)2/14/2015PDF299 kB
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AD7685 Results8/28/2019
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Accelerate Your Condition Monitoring with Voyager 37/23/2021PDF445 K
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Low-Power Data Conversion Technology Enhances Portability (Electropages, 10/5/2006)5/21/2015
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Lowest-Power 16-Bit ADC Optimizes Portable Designs (eeProductCenter, 10/4/2006)3/20/2015
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8- to 18-Bit SAR ADCs ... From the Leader in High Performance Analog3/8/2008PDF1885 kB
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The Data Conversion Handbook, 20051/2/2005
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MT-002: What the Nyquist Criterion Means to Your Sampled Data System Design2/14/2015PDF152 kB
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MT-031: Grounding Data Converters and Solving the Mystery of "AGND" and "DGND"3/20/2009PDF144 kB
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SAR ADC & Driver Quick-Match Guide9/13/2013PDF251 kB
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CN-0213:Complete High Speed, High CMRR Precision Analog Front End for Process Control6/5/2012PDF288 kB
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CN-0194: Galvanically Isolated, 2-Channel, 16-Bit, Simultaneous Sampling, Daisy-Chained Data Acquisition System1/26/2012PDF464 kB
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CN-0130: Integrated Device Power Supply (DPS) for ATE with Output Voltage Range 0 V to 25 V11/12/2010PDF231 kB
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CN-0104: Parametric Measurement Unit and Supporting Components for ATE Applications Using the AD5522 PMU and the AD7685 16-Bit ADC11/9/2010PDF247 kB
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Protecting ADC Inputs4/1/2017
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Simple Discrete SE-to-Differential Precision In-Amp Circuit: High Common-Mode Input Range and 50% Less Power10/1/2016
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Designing Power Supplies for High Speed ADC2/1/2012
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Seven Steps to Successful Analog-to-Digital Signal Conversion (Noise Calculation for Proper Signal Conditioning)5/1/2011
Software & Systems Requirements
Tools & Simulations
Precision ADC Driver Tool
The Precision ADC Driver Tool is a web application that simulates the performance of precision ADC and driver combinations. Potential issues with driver selection, kickback settling, and distortion are flagged, and design tradeoffs can be quickly evaluated. Simulations and calculations include system noise, distortion, and settling of the ADC input
Reference Designs (4)
Product Recommendations
AD7685 Companion Parts
Recommended Digital Isolators
- For SPI Interface, enhanced system-level ESD performance, 2.5 kVrms isolation: ADUM3401.
- For SPI Interface, smallest package, low voltage I/O (1.8 V to 5.5 V): ADUM3481.
- For SPI Interface, lowest power, 2.5 kVrms isolation: ADUM1401.
- For SPI Interface, low power, 5.0 kVrms isolation: ADUM4401.
Recommended Driver Amplifiers
- For precision, low power, low distortion applications: ADA4805-1, ADA4805-2, ADA4841-1, ADA4841-2.
- For high frequency, low noise, low distortion applications: ADA4807-1, ADA4807-2, ADA4897-1, ADA4897-2.
- For low frequency, precision, low bias current applications: ADA4627-1, ADA4637-1, AD8610.
Design Resources
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.
PCN-PDN Information
Support & Discussions
AD7685 Discussions
Sample & Buy
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Evaluation Boards
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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.