AD7986: 18-Bit, 2 MSPS PulSAR 15 mW ADC in LFCSP (QFN) Data Sheet (Rev. D)4/1/2009554 kB
Features and Benefits
- 18-bit resolution with no missing codes
- Throughput: 2 MSPS (TURBO = high), 1.5 MSPS (TURBO = low)
- Low power dissipation
- 15 mW at 2 MSPS, with external reference
- 26 mW at 2 MSPS with internal reference
- INL: ±1 LSB typical, ±2.5 LSB maximum
- 95.5 dB, with on-chip reference
- 97.0 dB, with external reference
- 4.096 V internal reference: typical drift of 10 ppm/°C
- True differential analog input voltage range: ±VREF
- 0 V to VREF with VREF up to 5.0 V
- Allows use of any input range
- See data sheet for additional features
The AD7986 is an 18-bit, 2 MSPS successive approximation, analog-to-digital converter (ADC). It contains a low power, high speed, 18-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 AD7986 samples the voltage difference between the IN+ and IN− pins. The voltages on these pins usually swing in opposite phases between 0 V and VREF. It features a very high sampling rate turbo mode (TURBO = high) and a reduced power normal mode (TURBO = low) for low power applications where the power is scaled with the throughput.
In normal mode (TURBO = low), the SPI-compatible serial interface also features the ability, using the SDI input, to daisychain 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 using the separate VIO supply.
The AD7986 is available in a 20-lead LFCSP with operation specified from −40°C to +85°C.
- Battery-powered equipment
- Data acquisition systems
- Medical instruments
- Seismic data acquisition systems
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)
The EVAL-AD7986FMCZ is a fully featured evaluation kit for the AD7986. This board operates in conjunction with the system development platform board, EVAL-SDP-CH1Z. When operated with the system development platform board, software is provided enabling the user to perform detailed analysis of the performance of the ADC. This software has an accompanying user guide describing the operation and set up of the evaluation board when operated with the system development platform board.
Documentation & Resources
AN-742: Frequency Domain Response of Switched-Capacitor ADCs (Rev. C)2/14/2015427 K
AN-931: Understanding PulSAR ADC Support Circuitry (Rev. 0)2/14/2015299 kB
UG-727: Evaluating the AD7944/AD7985/AD7986 14-/16-/18-Bit, PulSAR ADCs7/15/20151 M
The Data Conversion Handbook, 20051/2/2005
MT-002: What the Nyquist Criterion Means to Your Sampled Data System Design2/14/2015152 kB
MT-074: Differential Drivers for Precision ADCs2/14/2015249 kB
MT-031: Grounding Data Converters and Solving the Mystery of "AGND" and "DGND"3/20/2009144 kB
MT-001: Taking the Mystery out of the Infamous Formula, "SNR=6.02N + 1.76dB", and Why You Should Care3/4/200994 kB
SAR ADC & Driver Quick-Match Guide9/13/2013251 kB
Protecting ADC Inputs4/1/2017
Designing Power Supplies for High Speed ADC2/1/2012
Ultrahigh-Performance Differential-Output Programmable-Gain Instrumentation Amplifier for Data Acquisition10/1/2011 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
AD7986 Companion Parts
Recommended Digital Isolators
- For SPI Interface, enhanced system-level ESD performance, 2.5 kVrms isolation: ADUM3401.
- For SPI Interface, low power, 5.0 kVrms isolation: ADUM4401.
- For SPI Interface, lowest power, 2.5 kVrms isolation: ADUM1401.
- For SPI Interface, smallest package, low voltage I/O (1.8 V to 5.5 V): ADUM3481.
Recommended External Voltage References
Recommended Driver Amplifiers
- For low frequency, precision, low bias current applications: ADA4627-1, ADA4610-2, AD8476.
- For precision, low power, low distortion applications: ADA4841-1, ADA4940-1, ADA4941-1.
- For high frequency, low noise, low distortion applications: ADA4897-1, AD8021.
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.
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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.