JAJSPW8E march   2011  – february 2023 ADS4222 , ADS4225 , ADS4226 , ADS4242 , ADS4245 , ADS4246

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 Revision History
  5. 5 概要 (続き)
  6. 6 Pin Configuration and Functions
    1.     Pin Functions – LVDS Mode
    2.     Pin Functions – CMOS Mode
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics: ADS4246, ADS4245, ADS4242
    6. 7.6  Electrical Characteristics: ADS4226, ADS4225, ADS4222
    7. 7.7  Electrical Characteristics: General
    8. 7.8  Digital Characteristics
    9. 7.9  Timing Requirements: LVDS and CMOS Modes #GUID-C6C0701B-A11B-492F-BD6B-B774F5FE4665/SLAS6895399
    10. 7.10 Serial Interface Timing Characteristics #GUID-3852E7CE-C5B6-42F5-A56A-70AB1B981302/SBAS5097810
    11. 7.11 Reset Timing (Only When Serial Interface Is Used)
    12. 7.12 Typical Characteristics
      1. 7.12.1 ADS4246
      2. 7.12.2 ADS4245
      3. 7.12.3 ADS4242
      4. 7.12.4 ADS4226
      5. 7.12.5 ADS4225
      6. 7.12.6 ADS4222
      7. 7.12.7 General
      8. 7.12.8 Contour
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input
        1. 8.3.1.1 Drive Circuit Requirements
        2. 8.3.1.2 Driving Circuit
      2. 8.3.2 Clock Input
      3. 8.3.3 Digital Functions
      4. 8.3.4 Gain for SFDR/SNR Trade-off
      5. 8.3.5 Offset Correction
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Down
        1. 8.4.1.1 Global Power-Down
        2. 8.4.1.2 Channel Standby
        3. 8.4.1.3 Input Clock Stop
    5. 8.5 Programming
      1. 8.5.1 47
      2. 8.5.2 Parallel Configuration Only
      3. 8.5.3 Serial Interface Configuration Only
      4. 8.5.4 Using Both Serial Interface and Parallel Controls
      5. 8.5.5 Parallel Configuration Details
      6. 8.5.6 Serial Interface Details
        1. 8.5.6.1 Register Initialization
        2. 8.5.6.2 Serial Register Readout
      7. 8.5.7 Digital Output Information
        1. 8.5.7.1 Output Interface
        2. 8.5.7.2 DDR LVDS Outputs
        3. 8.5.7.3 LVDS Buffer
        4. 8.5.7.4 Parallel CMOS Interface
        5. 8.5.7.5 CMOS Interface Power Dissipation
        6. 8.5.7.6 Multiplexed Mode of Operation
        7. 8.5.7.7 Output Data Format
    6. 8.6 Register Maps
      1. 8.6.1 64
      2. 8.6.2 Description Of Serial Registers
  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
        1. 9.2.2.1 Analog Input
        2. 9.2.2.2 Clock Driver
        3. 9.2.2.3 Digital Interface
        4. 9.2.2.4 SNR and Clock Jitter
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Sharing DRVDD and AVDD Supplies
      2. 9.3.2 Using DC/DC Power Supplies
      3. 9.3.3 Power Supply Bypassing
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Grounding
        2. 9.4.1.2 Supply Decoupling
        3. 9.4.1.3 Exposed Pad
        4. 9.4.1.4 Routing Analog Inputs
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Device Nomenclature
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 サポート・リソース
    4. 10.4 商標
    5. 10.5 静電気放電に関する注意事項
    6. 10.6 用語集
  11. 11Mechanical, 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

8.3.4 Gain for SFDR/SNR Trade-off

The ADS424x/422x include gain settings that can be used to get improved SFDR performance (compared to no gain). The gain is programmable from 0 dB to 6 dB (in 0.5-dB steps). For each gain setting, the analog input full-scale range scales proportionally, as shown in Table 8-2.

The SFDR improvement is achieved at the expense of SNR; for each gain setting, the SNR degrades approximately between 0.5 dB and 1 dB. The SNR degradation is reduced at high input frequencies. As a result, the gain is very useful at high input frequencies because the SFDR improvement is significant with marginal degradation in SNR. Therefore, the gain can be used as a trade-off between SFDR and SNR. Note that the default gain after reset is 0 dB.

Table 8-2 Full-Scale Range Across Gains
GAIN (dB)TYPEFULL-SCALE (VPP)
0Default after reset2
1Fine, programmable1.78
2Fine, programmable1.59
3Fine, programmable1.42
4Fine, programmable1.26
5Fine, programmable1.12
6Fine, programmable1