JAJSTE0 March 2024 LMK05318B-Q1
PRODUCTION DATA
The XO input has a coarse frequency monitor to help qualify the input before the input is used to lock the APLLs.
The XO frequency detector clears the LOS_XO_FDET flag when the input frequency is detected within the supported range of 10MHz to 100MHz. The XO frequency monitor uses a RC-based detector and can not precisely detect if the XO input clock has sufficient frequency stability to verify successful VCO calibration during the PLL start-up when the external XO clock has a slow or delayed start-up behavior. See Slow or Delayed XO Start-Up for more information.
The XO frequency detector can be bypassed by setting the XO_FDET_BYP bit (shown as EN in Figure 7-16) so that the XO input is always considered valid by the PLL control state machine. The user can observe the LOS_XO_FDET status flag through the status pins and status bit.