SBAS872B December   2020  – October 2022 ADC3681 , ADC3682 , ADC3683

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics - Power Consumption
    6. 6.6  Electrical Characteristics - DC Specifications
    7. 6.7  Electrical Characteristics - AC Specifications
    8. 6.8  Timing Requirements
    9. 6.9  Typical Characteristics - ADC3681
    10. 6.10 Typical Characteristics - ADC3682
    11. 6.11 Typical Characteristics - ADC3683
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input
        1. 8.3.1.1 Analog Input Bandwidth
        2. 8.3.1.2 Analog Front End Design
          1. 8.3.1.2.1 Sampling Glitch Filter Design
          2. 8.3.1.2.2 Analog Input Termination and DC Bias
            1. 8.3.1.2.2.1 AC-Coupling
            2. 8.3.1.2.2.2 DC-Coupling
        3. 8.3.1.3 Auto-Zero Feature
      2. 8.3.2 Clock Input
        1. 8.3.2.1 Single Ended vs Differential Clock Input
        2. 8.3.2.2 Signal Acquisition Time Adjust
      3. 8.3.3 Voltage Reference
        1. 8.3.3.1 Internal voltage reference
        2. 8.3.3.2 External voltage reference (VREF)
        3. 8.3.3.3 External voltage reference with internal buffer (REFBUF)
      4. 8.3.4 Digital Down Converter
        1. 8.3.4.1 DDC MUX
        2. 8.3.4.2 Digital Filter Operation
        3. 8.3.4.3 FS/4 Mixing with Real Output
        4. 8.3.4.4 Numerically Controlled Oscillator (NCO) and Digital Mixer
        5. 8.3.4.5 Decimation Filter
        6. 8.3.4.6 SYNC
        7. 8.3.4.7 Output Formatting with Decimation
      5. 8.3.5 Digital Interface
        1. 8.3.5.1 Output Formatter
        2. 8.3.5.2 Output Scrambler
        3. 8.3.5.3 Output Bit Mapper
        4. 8.3.5.4 Output Interface/Mode Configuration
          1. 8.3.5.4.1 Configuration Example
        5. 8.3.5.5 Output Data Format
      6. 8.3.6 Test Pattern
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Operation
      2. 8.4.2 Power Down Options
      3. 8.4.3 Digital Channel Averaging
    5. 8.5 Programming
      1. 8.5.1 Configuration using PINs only
      2. 8.5.2 Configuration using the SPI interface
        1. 8.5.2.1 Register Write
        2. 8.5.2.2 Register Read
    6. 8.6 Register Map
      1. 8.6.1 Detailed Register Description
  9. 9 Application Information Disclaimer
    1. 9.1 Typical Application
      1. 9.1.1 Design Requirements
      2. 9.1.2 Detailed Design Procedure
        1. 9.1.2.1 Input Signal Path
        2. 9.1.2.2 Sampling Clock
        3. 9.1.2.3 Voltage Reference
      3. 9.1.3 Application Curves
    2. 9.2 Initialization Set Up
      1. 9.2.1 Register Initialization During Operation
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.4.1 Layout Guidelines

There are several critical signals which require specific care during board design:

  1. Analog input and clock signals
    • Traces should be as short as possible and vias should be avoided where possible to minimize impedance discontinuities.
    • Traces should be routed using loosely coupled 100-Ω differential traces.
    • Differential trace lengths should be matched as close as possible to minimize phase imbalance and HD2 degradation.
  2. Digital output interface
    • Traces should be routed using tightly coupled 100-Ω differential traces.
  3. Voltage reference
    • The bypass capacitor should be placed as close to the device pins as possible and connected between VREF and REFGND – on top layer avoiding vias.
    • Depending on configuration an additional bypass capacitor between REFBUF and REFGND may be recommended and should also be placed as close to pins as possible on top layer.
  4. Power and ground connections
    • Provide low resistance connection paths to all power and ground pins.
    • Use power and ground planes instead of traces.
    • Avoid narrow, isolated paths which increase the connection resistance.
    • Use a signal/ground/power circuit board stackup to maximize coupling between the ground and power plane.