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
- Data acquisition systems
- Medical instruments
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.
The EVAL-AD7985FMCZ is a fully featured evaluation kit for the AD7985. 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.
Recommended Digital Isolators
- For SPI Interface, smallest package, low voltage I/O (1.8 V to 5.5 V) , we recommend the ADUM3481 .
- 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 .
Recommended External Voltage References
- 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, AD8031 or the AD8605 .
- 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 recommend the ADR433 or the ADR4533 .
Recommended Driver Amplifiers
- For precision, low power, low distortion applications , we recommend the ADA4841-1, ADA4896-2, AD8031 or the AD8031 .
- For low frequency, precision, low bias current applications , we recommend the ADA4627-1, ADA4637-1 or the AD8610 .
- For high frequency, low noise, low distortion applications , we recommend the ADA4897-1 or the AD8021 .
Product Selection Guide
SAR ADC & Driver Quick-Match Guide
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MS-2689: Isolating SPI for High Bandwidth Sensors
MS-1779: Nine Often Overlooked ADC Specifications
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Designing Power Supplies for High Speed ADC
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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.
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.