SNAU252 June   2020 LMK04832-SP

 

  1.   LMK04832EVM-CVAL User’s Guide
    1.     Trademarks
    2. 1  Evaluation Board Kit Contents
    3. 2  Quick Start
      1. 2.1 Quick Start Description
        1. 2.1.1 Clock Outputs Page Description
        2. 2.1.2 TICS Pro Tips
    4. 3  PLL Loop Filters and Loop Parameters
      1. 3.1 PLL1 Loop Filter
      2. 3.2 PLL2 Loop Filter
    5. 4  Default TICS Pro Mode
    6. 5  Using TICS Pro to Program the LMK04832-SP
      1. 5.1 Start TICS Pro Application
      2. 5.2 Select Device
      3. 5.3 Program the Device
      4. 5.4 Restoring a Default Mode
      5. 5.5 Visual Confirmation of Frequency Lock
      6. 5.6 Enable Clock Outputs
    7. 6  Evaluation Board Inputs and Outputs
    8. 7  Recommended Test Equipment
    9. 8  Length Matching
    10. 9  Schematics
    11. 10 Bill of Materials
  2.   A TICS Pro Usage
    1.     A.1 Communication Setup
    2.     A.2 User Controls
    3.     A.3 Raw Registers Page
    4.     A.4 Set Modes Page
    5.     A.5 Holdover Page
    6.     A.6 CLKinX Control Page
    7.     A.7 PLL1 and 2 Page
    8.     A.8 SYNC / SYSREF Page
    9.     A.9 Clock Outputs Page
    10.     A.10 Other Page
    11.     A.11 Current Calculator Page
    12.     A.12 Burst Page

A.5 Holdover Page

The Holdover page contains many registers pertaining to how the device will enter and exit holdover. To enable holdover and LOS detect for entry and exit of holdover:

  • Set HOLDOVER_EN = 1 (checked).
  • Set HOLDOVER_EXIT_MODE combo box to 0x00 (Exit based on LOS).
  • Set LOS_EN = 1 (checked).
  • Set LOS_TIMEOUT combo box to the LOS frequency threshold as desired. For example, if 200 MHz is set as the frequency threshold, the input must be above approximately 200 MHz to lock, otherwise PLL1 will enter holdover. If holdover is not enabled, PLL1 will be prevented from locking if the input frequency is less than the threshold frequency and LOS is enabled.

In addition to the above steps, auto clock selection mode must be used to allow the LMK04832-SP to automatically switch to holdover when enabled clocks for auto switching (CLKinX_EN) are lost.

holdover_snau252.gifFigure 17. TICS Pro - Holdover Page