SBAS603B April   2013  – November 2020 ADS4449

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
    6. 6.6  Digital Characteristics
    7. 6.7  Timing Requirements
    8. 6.8  Timing Characteristics, Serial interface
    9. 6.9  Typical Characteristics
    10. 6.10 Typical Characteristics: Contour
  7. 7 Parameter Measurement Information
    1. 7.1 LVDS Output Timing
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Overrange Indication (OVRxx)
      2. 8.3.2 Gain for SFDR and SNR Trade-Off
    4. 8.4 Device Functional Modes
      1. 8.4.1 Special Performance Modes
      2. 8.4.2 Digital Output Information
        1. 8.4.2.1 DDR LVDS Outputs
          1. 8.4.2.1.1 LVDS Output Data and Clock Buffers
          2. 8.4.2.1.2 Output Data Format
      3. 8.4.3 Using High SNR Mode Register Settings
      4. 8.4.4 Input Common Mode
    5. 8.5 Programming
      1. 8.5.1 Serial Interface
        1. 8.5.1.1 Register Initialization
        2. 8.5.1.2 Serial Register Readout
    6. 8.6 Register Maps
      1. 8.6.1 Register Description
        1. 8.6.1.1  Register Address 00h (Default = 00h)
        2. 8.6.1.2  Register Address 01h (Default = 00h)
        3. 8.6.1.3  Register Address 25h (Default = 00h)
        4. 8.6.1.4  Register Address 2bh (Default = 00h)
        5. 8.6.1.5  Register Address 31h (Default = 00h)
        6. 8.6.1.6  Register Address 37h (Default = 00h)
        7. 8.6.1.7  Register Address 3dh (Default = 00h)
        8. 8.6.1.8  Register Address 3fh (Default = 00h)
        9. 8.6.1.9  Register Address 40h (Default = 00h)
        10. 8.6.1.10 Register Address 42h (Default = 00h)
        11. 8.6.1.11 Register Address 45h (Default = 00h)
        12. 8.6.1.12 Register Address 4ah (Defalut = 00h)
        13. 8.6.1.13 Register Address 62h (Default = 00h)
        14. 8.6.1.14 Register Address 7ah (Default = 00h)
        15. 8.6.1.15 Register Address 92h (Default = 00h)
        16. 8.6.1.16 Register Address A9h (Default = 00h)
        17. 8.6.1.17 Register Address Ach (Default = 00h)
        18. 8.6.1.18 Register Address C3h (Default = 00h)
        19. 8.6.1.19 Register Address C4h (Default = 00h)
        20. 8.6.1.20 Register Address Cfh (Default = 00h)
        21. 8.6.1.21 Register Address D6h (Default = 00h)
        22. 8.6.1.22 Register Address D7h (Default = 00h)
        23. 8.6.1.23 Register Address F1h (Default = 00h)
        24. 8.6.1.24 Register Address 58h (Default = 00h)
        25. 8.6.1.25 Register Address 59h (Default = 00h)
        26. 8.6.1.26 Register Address 70h (Default = 00h)
        27. 8.6.1.27 Register Address 71h (Default = 00h)
        28. 8.6.1.28 Register Address 88h (Default = 00h)
        29. 8.6.1.29 Register Address 89h (Default = 00h)
        30. 8.6.1.30 Register Address A0h (Default = 00h)
        31. 8.6.1.31 Register Address A1h (Default = 00h)
        32. 8.6.1.32 Register Address Feh (Default = 00h)
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
      4. 9.2.4 Enabling 14-Bit Resolution
      5. 9.2.5 Analog Input
      6. 9.2.6 Drive Circuit Requirements
      7. 9.2.7 Clock Input
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Nomenclature
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary

Package Options

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

8.4.3 Using High SNR Mode Register Settings

The HIGH SNR MODE register settings can be used to further improve the SNR. However, there is a trade off between improved SNR and degraded THD when these settings are used. These settings shut down the internal spectrum-cleaning algorithm, resulting in THD performance degradation. Figure 8-6 and Figure 8-7 show the effect of using HIGH SNR MODE. SNR improves by approximately 1 dB and THD degrades by 3 dB.

GUID-1E89627F-7A23-4F11-92D7-E28601EA8E95-low.png
fIN = 170 MHzSFDR = 93 dBcSNR = 69.1 dBFS
SINAD = 69 dBFSTHD = 89 dBc
Figure 8-6 FFT (Default) at 170 MHz
GUID-CB50E756-D9FC-4250-BABC-0C00D544DC90-low.png
fIN = 170 MHzSFDR = 89 dBcSNR = 70.1 dBFS
SINAD = 70 dBFSTHD = 86 dBc
Figure 8-7 FFT with High SNR Mode at 170 MHz

Figure 8-8 shows SNR versus input frequency with and without these settings.

GUID-662DA739-77BA-495B-80C1-F6AF517A6CF4-low.pngFigure 8-8 SNR vs Input Frequency with High SNR Mode

To obtain best performance, TI recommends keeping termination impedance between INP and INM low (for instance, at 50 Ω differential). This setting helps absorb the kickback noise component of the spectrum-cleaning algorithm. However, when higher termination impedances (such as 100 Ω) are required, shutting down the spectrum-cleaning algorithm by using the HIGH SNR MODE register settings can be helpful.