SBAS886A October   2020  – May 2022 ADC3641 , ADC3642 , ADC3643

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 ADC3641
    8. 6.8  Electrical Characteristics - AC Specifications ADC3642
    9. 6.9  Electrical Characteristics - AC Specifications ADC3643
    10. 6.10 Timing Requirements
    11. 6.11 Typical Characteristics - ADC3641
    12. 6.12 Typical Characteristics - ADC3642
    13. 6.13 Typical Characteristics - ADC3643
  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 Single Ended Input
          3. 8.3.1.2.3 Analog Input Termination and DC Bias
            1. 8.3.1.2.3.1 AC-Coupling
            2. 8.3.1.2.3.2 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
          1. 8.3.4.2.1 FS/4 Mixing with Real Output
        3. 8.3.4.3 Numerically Controlled Oscillator (NCO) and Digital Mixer
        4. 8.3.4.4 Decimation Filter
        5. 8.3.4.5 SYNC
        6. 8.3.4.6 Output Formatting with Decimation
          1. 8.3.4.6.1 Parallel CMOS
          2. 8.3.4.6.2 Serialized CMOS
      5. 8.3.5 Digital Interface
        1. 8.3.5.1 Parallel CMOS Output
        2. 8.3.5.2 Serialized CMOS output
          1. 8.3.5.2.1 SDR Output Clocking
        3. 8.3.5.3 Output Data Format
        4. 8.3.5.4 Output Formatter
        5. 8.3.5.5 Output Bit Mapper
        6. 8.3.5.6 Output Interface/Mode Configuration
          1. 8.3.5.6.1 Configuration Example
      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
    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 Maps
      1. 8.6.1 Detailed Register Description
  9. 9 Application and Implementation
    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
    • A 20 Ω series isolation resistor should be used on each CMOS output and placed close the digital output. This isolation resistor limits the output current into the capacitive load and thus minimizes the switching noise inside the ADC. When driving longer distances a buffer should be used. The resistor value should be optimized for the desired output data rate.
  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.