SBAS728B November   2016  – May 2026 ADS8900B , ADS8902B , ADS8904B

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Switching Characteristics
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 LDO Module
      2. 6.3.2 Reference Buffer Module
      3. 6.3.3 Converter Module
        1. 6.3.3.1 Sample-and-Hold Circuit
        2. 6.3.3.2 Internal Oscillator
        3. 6.3.3.3 ADC Transfer Function
      4. 6.3.4 Interface Module
    4. 6.4 Device Functional Modes
      1. 6.4.1 RST State
      2. 6.4.2 ACQ State
      3. 6.4.3 CNV State
    5. 6.5 Programming
      1. 6.5.1 Output Data Word
      2. 6.5.2 Data Transfer Frame
      3. 6.5.3 Interleaving Conversion Cycles and Data Transfer Frames
      4. 6.5.4 Data Transfer Protocols
        1. 6.5.4.1 Protocols for Configuring the Device
        2. 6.5.4.2 Protocols for Reading From the Device
          1. 6.5.4.2.1 Legacy, SPI-Compatible (SYS-xy-S) Protocols
          2. 6.5.4.2.2 SPI-Compatible Protocols with Bus Width Options
          3. 6.5.4.2.3 Source-Synchronous (SRC) Protocols
            1. 6.5.4.2.3.1 Output Clock Source Options with SRC Protocols
            2. 6.5.4.2.3.2 Bus Width Options With SRC Protocols
            3. 6.5.4.2.3.3 Output Data Rate Options With SRC Protocols
      5. 6.5.5 Device Setup
        1. 6.5.5.1 Single Device: All multiSPI Options
        2. 6.5.5.2 Single Device: Minimum Pins for a Standard SPI Interface
        3. 6.5.5.3 Multiple Devices: Daisy-Chain Topology
        4. 6.5.5.4 Multiple Devices: Star Topology
  8. 7 Register Maps
    1. 7.1 Device Configuration and Register Maps
      1. 7.1.1 PD_CNTL Register (address = 04h) [reset = 00h]
      2. 7.1.2 SDI_CNTL Register (address = 008h) [reset = 00h]
      3. 7.1.3 SDO_CNTL Register (address = 0Ch) [reset = 00h]
      4. 7.1.4 DATA_CNTL Register (address = 010h) [reset = 00h]
      5. 7.1.5 PATN_LSB Register (address = 014h) [reset = 00h]
      6. 7.1.6 PATN_MID Register (address = 015h) [reset = 00h]
      7. 7.1.7 PATN_MSB Register (address = 016h) [reset = 00h]
      8. 7.1.8 OFST_CAL Register (address = 020h) [reset = 00h]
      9. 7.1.9 REF_MRG Register (address = 030h) [reset = 00h]
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 ADC Reference Driver
      2. 8.1.2 ADC Input Driver
        1. 8.1.2.1 Charge-Kickback Filter
        2. 8.1.2.2 Input Amplifier Selection
    2. 8.2 Typical Application
      1. 8.2.1 Data Acquisition (DAQ) Circuit for Lowest Distortion and Noise Performance With Differential Input
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 DAQ Circuit With FDA Input Driver and Single-Ended or Differential Input
      3. 8.2.3 Design Requirements
      4. 8.2.4 Detailed Design Procedure
      5. 8.2.5 Application Curves
  10. 9 Power-Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Signal Path
      2. 10.1.2 Grounding and PCB Stack-Up
      3. 10.1.3 Decoupling of Power Supplies
      4. 10.1.4 Reference Decoupling
      5. 10.1.5 Differential Input Decoupling
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

10.1.4 Reference Decoupling

Dynamic currents are also present at the REFBUFOUT and REFM pins during the conversion phase, and excellent decoupling is required to achieve optimum performance. Place a 22-μF, X7R-grade, ceramic capacitor with at least 10-V rating and an ESR of 1-Ω between the REFBUFOUT and the REFM pins, as illustrated in Figure 10-1. Select 0603- or 0805-size capacitors to keep equivalent series inductance (ESL) low. Connect the REFM pins to the decoupling capacitor before a ground via.