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.
|Title||Content Type||File Type|
|AD7985: 16-Bit, 2.5 MSPS, PulSAR 15.5 mW ADC in LFCSP Data Sheet (Rev A, 08/2010) (pdf, 656 kB)||Data Sheets|
|AN-1141: Powering a Dual Supply Precision ADC with Switching Regulators (pdf, 640 kB)||Application Notes|
|AN-877: Interfacing to High Speed ADCs via SPI (pdf, 1594 kB)||Application Notes|
|AN-935: Designing an ADC Transformer-Coupled Front End (pdf, 363 kB)||Application Notes|
|AN-742: Frequency Domain Response of Switched-Capacitor ADCs (pdf, 401 kB)||Application Notes|
|CN-0260: Oversampled SAR ADC with PGA Achieving Greater Than 125 dB Dynamic Range (pdf)||Circuit Note|
|The Data Conversion Handbook||Design Handbooks||HTML|
|MT-031: Grounding Data Converters and Solving the Mystery of (pdf, 144 kB)||Tutorials|
|MT-002: What the Nyquist Criterion Means to Your Sampled Data System Design (pdf, 152 kB)||Tutorials|
|MT-001: Taking the Mystery out of the Infamous Formula, "SNR=6.02N + 1.76dB," and Why You Should Care (pdf, 94 kB)||Tutorials|
|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|
|MS-2022: Seven Steps to Successful Analog-to-Digital Signal Conversion (Noise Calculation for Proper Signal Conditioning) (pdf, 277 kB)||Technical Articles|
|MS-2124: Understanding AC Behaviors of High Speed ADCs (pdf, 276 kB)||Technical Articles|
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.
|RAQs index||Rarely Asked Questions||HTML|
|Glossary of EE Terms||Glossary||HTML|
Recommended Driver Amplifiers for the AD7985
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