SBAS558C December   2012  – December 2015 ADS42B49

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 ADS424x and ADS422x Family Comparison
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1  Absolute Maximum Ratings
    2. 8.2  ESD Ratings
    3. 8.3  Recommended Operating Conditions
    4. 8.4  Thermal Information
    5. 8.5  Electrical Characteristics: ADS42B49 (250 MSPS)
    6. 8.6  Electrical Characteristics: General
    7. 8.7  Digital Characteristics
    8. 8.8  Timing Requirements: LVDS and CMOS Modes
    9. 8.9  Serial Interface Timing Characteristics
    10. 8.10 Reset Timing (Only When Serial Interface is Used)
    11. 8.11 LVDS Timings at Lower Sampling Frequencies
    12. 8.12 CMOS Timings at Lower Sampling Frequencies
    13. 8.13 Typical Characteristics
      1. 8.13.1 ADS42B49
      2. 8.13.2 Contour
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1 Migrating from the ADS62P49 and ADS4249
      2. 10.3.2 Digital Functions
      3. 10.3.3 Gain for SFDR and SNR Trade-Off
      4. 10.3.4 Offset Correction
    4. 10.4 Device Functional Modes
      1. 10.4.1 Power-Down
        1. 10.4.1.1 Global Power-Down
        2. 10.4.1.2 Channel Standby
        3. 10.4.1.3 Input Clock Stop
      2. 10.4.2 Digital Output Information
        1. 10.4.2.1 Output Interface
        2. 10.4.2.2 DDR LVDS Outputs
        3. 10.4.2.3 LVDS Buffer
        4. 10.4.2.4 Parallel CMOS Interface
        5. 10.4.2.5 CMOS Interface Power Dissipation
        6. 10.4.2.6 Multiplexed Mode of Operation
        7. 10.4.2.7 Output Data Format
      3. 10.4.3 Parallel Configuration Details
    5. 10.5 Programming
      1. 10.5.1 Parallel Configuration Only
      2. 10.5.2 Serial Interface Configuration Only
      3. 10.5.3 Using Both Serial Interface and Parallel Controls
      4. 10.5.4 Serial Interface Details
        1. 10.5.4.1 Register Initialization
        2. 10.5.4.2 Serial Register Readout
    6. 10.6 Register Maps
      1. 10.6.1 Register Description
  11. 11Application and Implementation
    1. 11.1 Application Information
      1. 11.1.1 Driving Circuit
        1. 11.1.1.1 Drive Circuit Requirements
      2. 11.1.2 Clock Input
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Analog Input
        2. 11.2.2.2 Clock Driver
        3. 11.2.2.3 Digital Interface
      3. 11.2.3 Application Curves
  12. 12Power Supply Recommendations
    1. 12.1 Using DC/DC Power Supplies
    2. 12.2 Power Supply Bypassing
  13. 13Layout
    1. 13.1 Layout Guidelines
      1. 13.1.1 Grounding
      2. 13.1.2 Supply Decoupling
      3. 13.1.3 Exposed Pad
      4. 13.1.4 Routing Analog Inputs
    2. 13.2 Layout Example
  14. 14Device and Documentation Support
    1. 14.1 Device Support
      1. 14.1.1 Device Nomenclature
    2. 14.2 Documentation Support
      1. 14.2.1 Related Documentation
    3. 14.3 Community Resources
    4. 14.4 Trademarks
    5. 14.5 Electrostatic Discharge Caution
    6. 14.6 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

13 Layout

13.1 Layout Guidelines

13.1.1 Grounding

A single ground plane is sufficient to give good performance, provided the analog, digital, and clock sections of the board are cleanly partitioned. Download the ADS42xx_58C28EVM DesignPkg file from the ADS42B49EVM product folder on the TI website for details on layout and grounding.

13.1.2 Supply Decoupling

Because the ADS42B49 already includes internal decoupling, minimal external decoupling can be used without loss in performance. Decoupling capacitors can help filter external power-supply noise; thus, the optimum number of capacitors depends on the actual application. The decoupling capacitors should be placed very close to the converter supply pins.

13.1.3 Exposed Pad

In addition to providing a path for heat dissipation, the PowerPAD is also electrically connected internally to the digital ground. Thus, the exposed pad must be soldered to the ground plane for best thermal and electrical performance. For detailed information, see application notes QFN Layout Guidelines (SLOA122) and QFN/SON PCB Attachment (SLUA271).

13.1.4 Routing Analog Inputs

TI advises routing differential analog input pairs (INP_x and INM_x) close to each other. To minimize the possibility of coupling from a channel analog input to the sampling clock, the analog input pairs of both channels should be routed perpendicular to the sampling clock; see the ADS42Bx EVM User's Guide (SLAU477) for reference routing. Figure 65 shows a snapshot of the PCB layout from the ADS42xxEVM.

13.2 Layout Example

ADS42B49 ai_pcb_snapshot_bas550.gif Figure 65. ADS42xxEVM PCB Layout