SNAS851A December   2023  – May 2025 LMX1906-SP

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 Timing Diagram
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
      1. 6.1.1 Range of Dividers and Multiplier
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Power On Reset
      2. 6.3.2 Temperature Sensor
      3. 6.3.3 Clock Outputs
        1. 6.3.3.1 Clock Output Buffers
        2. 6.3.3.2 Clock MUX
        3. 6.3.3.3 Clock Divider
        4. 6.3.3.4 Clock Multiplier
          1. 6.3.3.4.1 General Information about the Clock Multiplier
          2. 6.3.3.4.2 State Machine Clock for the Clock Multiplier
            1. 6.3.3.4.2.1 State Machine Clock
          3. 6.3.3.4.3 Calibration for the Clock Multiplier
          4. 6.3.3.4.4 Lock Detect for the Clock Multiplier
          5. 6.3.3.4.5 Watchdog Timer
      4. 6.3.4 LOGICLK Output
        1. 6.3.4.1 LOGICLK Output Format
        2. 6.3.4.2 LOGICLK_DIV_PRE and LOGICLK_DIV Dividers
      5. 6.3.5 SYSREF
        1. 6.3.5.1 SYSREF Output Buffers
          1. 6.3.5.1.1 SYSREF Output Buffers for Main Clocks (SYSREFOUT)
          2. 6.3.5.1.2 SYSREF Output Buffer for LOGICLK
        2. 6.3.5.2 SYSREF Frequency and Delay Generation
        3. 6.3.5.3 SYSREFREQ Pins and SYSREFREQ_FORCE Field
          1. 6.3.5.3.1 SYSREFREQ Pins Common-Mode Voltage
          2. 6.3.5.3.2 SYSREFREQ Windowing Feature
            1. 6.3.5.3.2.1 General Procedure Flowchart for SYSREF Windowing Operation
            2. 6.3.5.3.2.2 SYSREFREQ Repeater Mode With Delay Generation (Retime)
            3. 6.3.5.3.2.3 Other Guidance For SYSREF Windowing
            4. 6.3.5.3.2.4 For Glitch-Free Output
            5. 6.3.5.3.2.5 If Using SYNC Feature
          3. 6.3.5.3.3 SYNC Feature
    4. 6.4 Device Functional Modes Configurations
      1. 6.4.1 Pin Mode Control
        1. 6.4.1.1 Chip Enable (CE)
        2. 6.4.1.2 Output Channel Control
        3. 6.4.1.3 Logic Output Control
        4. 6.4.1.4 SYSREF Output Control
        5. 6.4.1.5 Device Mode Selection
        6. 6.4.1.6 Divider or Multiplier Value Selection
        7. 6.4.1.7 Calibration Control Pin
        8. 6.4.1.8 Output Power Control
  8. 7 Register Map
    1. 7.1 Device Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 SYSREFREQ Input Configuration
      2. 8.1.2 Treatment of Unused Pins
      3. 8.1.3 Current Consumption
    2. 8.2 Typical Applications
      1. 8.2.1 Local Oscillator Distribution Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Plot
      2. 8.2.2 JESD204B/C Clock Distribution Application
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Power-Up Timing
    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 Device Support
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

6.3.5.3 SYSREFREQ Pins and SYSREFREQ_FORCE Field

The SYSREFREQ pins are multipurpose and can be used for SYNC, SYSREF requests, and SYSREF windowing. These pins can be DC or AC coupled and have individual 50Ω, single-ended termination with programmable common-mode support.

In addition to these pins, the SYSREFREQ_FORCE field can be set to 1 to emulate the same effect as forcing these pins high, simplifying hardware in some cases.