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AD7985: 16-Bit, 2.5 MSPS, PulSAR 15.5 mW ADC in LFCSP Data Sheet (Rev. C)9/1/2009PDF656 kB
Overview
Features and Benefits
- 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
- See data sheet for additional features
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.
Applications
- Battery-powered equipment
- Communications
- ATE
- Data acquisition systems
- Medical instruments
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 (1)
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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UG-727: Evaluating the AD7944/AD7985/AD7986 14-/16-/18-Bit, PulSAR ADCs7/15/2015PDF1 M
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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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Protecting ADC Inputs4/1/2017
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Isolating SPI for High Bandwidth Sensors8/1/2014
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Successive-Approximation ADCs: Ensuring a Valid First Conversion12/1/2013 Analog Dialogue
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Designing Power Supplies for High Speed ADC2/1/2012
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Oversampled ADC and PGA Combine to Provide 127-dB Dynamic Range12/1/2011 Analog Dialogue
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
IBIS Models
IBS
AD7944/AD7985/AD7986 IBIS Model
68.51 K
Reference Designs (1)
Product Recommendations
AD7985 Companion Parts
Recommended Digital Isolators
- 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, enhanced system-level ESD performance, 2.5 kVrms isolation: ADUM3401.
- For SPI Interface, low power, 5.0 kVrms isolation: ADUM4401.
Recommended External Voltage References
Recommended Driver Amplifiers
- For precision, low power, low distortion applications: ADA4841-1, ADA4896-2, AD8031, AD8031.
- For low frequency, precision, low bias current applications: ADA4627-1, ADA4637-1, AD8610.
- For high frequency, low noise, low distortion applications: ADA4897-1, AD8021.
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
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.