Holdover Page
29
SNAU252 – June 2020
Copyright © 2020, Texas Instruments Incorporated
TICS Pro Usage
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.
Figure 17. TICS Pro - Holdover Page
