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.
For additional ADI Healthcare Products and related information, please visit www.analog.com/healthcare.
|Title||Content Type||File Type|
|AD7685: 16-Bit, 250 kSPS PulSAR ADC in MSOP/QFN Data Sheet (Rev C, 08/2011) (pdf, 634 kB)||Data Sheets|
|Tested ADC Driver to PulSAR ADC||Application Notes||HTML|
|AN-1141: Powering a Dual Supply Precision ADC with Switching Regulators (pdf, 640 kB)||Application Notes|
AN-931: Understanding PulSAR ADC Support Circuitry
(pdf, 299 kB)
This application note discusses in general the pitfalls that occur regularly when using SAR ADCs and, more importantly, how to easily prevent them.
|AN-932: Power Supply Sequencing (pdf, 95 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-0213:Complete High Speed, High CMRR Precision Analog Front End for Process Control (pdf, 288 kB)||Circuit Note|
|CN-0194: Galvanically Isolated, 2-Channel, 16-Bit, Simultaneous Sampling, Daisy-Chained Data Acquisition System (pdf, 464 kB)||Circuit Note|
|CN-0130: Integrated Device Power Supply (DPS) for ATE with Output Voltage Range 0 V to 25 V (pdf, 231 kB)||Circuit Note|
|CN-0104: Parametric Measurement Unit and Supporting Components for ATE Applications Using the AD5522 PMU and the AD7685 16-Bit ADC (pdf, 247 kB)||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|
|UG-340: Evaluation Board for the 10-Lead Family 14-/16-/18-Bit PulSAR ADCs (pdf, 4636 kB)||User Guides|
Voltage Reference Design for Precision Successive-Approximation ADCs
(Analog Dialogue, Volume 47 – June 2013)
High Speed Op Amp Drives a 16-Bit, 1-MSPS Differential-Input A/D Converter
(Analog Dialogue, Vol. 36, No. 6, November/December 2002)
|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.
|Low Cost, Low Power, High Performance AED||Technical Articles||HTML|
|ICs for Low Power, Low Cost ECG Holter Monitors Support Standard Medical Wireless Bands||Technical Articles||HTML|
Low-Power Data Conversion Technology Enhances Portability
Lowest-Power 16-Bit ADC Optimizes Portable Designs
SAR ADC & Driver Quick-Match Guide
(pdf, 251 kB)
Find drivers for ADI's most popular single-ended and differential SAR ADCs based on your specific application conditions.
|Product Selection Guide|
|When high performance and low power make the design, ADI converters make the difference.||Overview||HTML|
8- to 18-Bit SAR ADCs ... From the Leader in High Performance Analog
(pdf, 1885 kB)
8- to 18-Bit SAR ADCs with Sample Rates up to 3 MSPS -- The latest additions to ADI’s ADC portfolio offer unrivaled functionality in terms of channel count and power supply voltage, optimal power/speed ratios, and the smallest packages to meet the demands of any data acquisition application, including portable, industrial, medical, wireless, and communications.
High Speed, High Accuracy 14-Bit, 16-Bit, and 18-Bit PulSAR ADCs
(pdf, 3826 kB)
A PulSAR Family Brochure (6/2006)
|RAQs index||Rarely Asked Questions||HTML|
|Glossary of EE Terms||Glossary||HTML|
|Title||Content Type||File Type|
|AD7685 IBIS Models||IBIS Models||HTML|
|BeMicro FPGA Project for CN0194 with Nios driver||FPGA HDL||HTML|
|BeMicro FPGA Project for AD7685 with Nios driver||FPGA HDL||HTML|
|CN0194 FMC-SDP Interposer & Evaluation Board / Xilinx KC705 Reference Design||FPGA HDL||HTML|
|AD7685 FMC-SDP Interposer & Evaluation Board / Xilinx KC705 Reference Design||FPGA HDL||HTML|
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