Overview

Features and Benefits

  • 16-bit resolution with no missing codes
  • Throughput: 250 kSPS
  • INL: ±0.6 LSB typical, ±2 LSB maximum (±0.003% of FSR)
  • SINAD: 93.5 dB @ 20 kHz
  • THD: −110 dB @ 20 kHz
  • Pseudo differential analog input range 0 V to VREF with VREF up to VDD
  • No pipeline delay
  • Single-supply operation 2.3 V to 5.5 V with 1.8 V to 5 V logic interface
  • Serial interface SPI®-/QSPI-/MICROWIRE-/DSP-compatible
  • Daisy-chain multiple ADCs, BUSY indicator
  • Power dissipation
    1.4 μW @ 2.5 V/100 SPS
    1.35 mW @ 2.5 V/100 kSPS, 4 mW @ 5 V/100 kSPS
  • Standby current: 1 nA

Product Details

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.

Applications

  • Battery-powered equipment
  • Medical instruments
  • Mobile communications
  • Personal digital assistants (PDAs)
  • Data acquisition
  • Instrumentation
  • Process controls

Product Lifecycle icon-recommended 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 (2)

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

Precision-ADC-Driver-2

IBIS Models

AD7685 IBIS Models

Reference Designs (4)

Product Recommendations

AD7685 Companion Parts

Recommended Digital Isolators

  • For SPI Interface, enhanced system-level ESD performance, 2.5 kVrms isolation: ADUM3401.
  • 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, low power, 5.0 kVrms isolation: ADUM4401.

Recommended Driver Amplifiers

Recommended External Voltage Reference

Recommended Voltage Regulators

  • For high current switching regulators with inputs up to 5V: ADP2114.
  • For low dropout regulators with inputs up to 5V: ADP151, ADP160.

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

Discussions

AD7685 Discussions

RE: AD7685 Reading data problem
9 week(s) ago in Precision ADCs
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Evaluation Boards Pricing displayed is based on 1-piece.
Up to two boards can be purchased through Analog.com. To order more than two, please purchase through one of our listed distributors.
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.