SBASB68 August   2025 ADS9803

PRODMIX  

  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 Timing Diagrams
    9. 5.9 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 Analog Inputs
        1. 6.3.1.1 Input Clamp Protection Circuit
        2. 6.3.1.2 Programmable Gain Amplifier (PGA)
        3. 6.3.1.3 Wide-Common-Mode Voltage Rejection Circuit
      2. 6.3.2 ADC Transfer Function
      3. 6.3.3 ADC Sampling Clock Input
      4. 6.3.4 Synchronizing Multiple ADCs
      5. 6.3.5 Reference Voltage
      6. 6.3.6 Data Interface
        1. 6.3.6.1 Data Clock Output
        2. 6.3.6.2 ADC Output Data Randomizer
        3. 6.3.6.3 Data Averaging
        4. 6.3.6.4 Test Patterns for Data Interface
          1. 6.3.6.4.1 Fixed Pattern
          2. 6.3.6.4.2 Digital Ramp
          3. 6.3.6.4.3 Alternating Test Pattern
    4. 6.4 Device Functional Modes
      1. 6.4.1 Reset
      2. 6.4.2 Power-Down
      3. 6.4.3 Initialization Sequence
      4. 6.4.4 Normal Operation
      5. 6.4.5 Speed-Boost Mode
    5. 6.5 Programming
      1. 6.5.1 Register Write
      2. 6.5.2 Register Read
      3. 6.5.3 Multiple Devices in a Daisy-Chain Topology for SPI Configuration
        1. 6.5.3.1 Register Write With Daisy-Chain
        2. 6.5.3.2 Register Read With Daisy-Chain
  8. 7 Register Map
    1. 7.1 Register Bank 0
    2. 7.2 Register Bank 1
    3. 7.3 Register Bank 2
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Parametric Measurement Unit (PMU)
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
      4. 8.2.4 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

6.5.3.1 Register Write With Daisy-Chain

Writing to registers in daisy-chain requires N × 24 SCLKs in one SPI frame. As depicted in Figure 6-13, a register write operation in a daisy-chain containing four ADCs requires 96 SCLKs.

Daisy-chain mode is enabled on power-up or after device reset. Configure the DAISY_CHAIN_LEN field to enable daisy-chain mode. Repeat the waveform shown in Figure 6-14 N times, where N is the number of ADCs in daisy-chain. Figure 6-15 provides the SPI waveform, containing N SPI frames, for enabling daisy-chain mode for N ADCs.

ADS9801 ADS9803 Register Write With Daisy-Chain Figure 6-14 Register Write With Daisy-Chain
ADS9801 ADS9803 Register Write to Configure the Daisy-Chain Length Figure 6-15 Register Write to Configure the Daisy-Chain Length