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LMK04828: SYNC event required after input port change?

Jade Goo
Intellectual 1940 points

Part Number: LMK04828

Hi Team,

When customer change input port during the operation, does SYNC event required again?
For example,

CLK0:10MHz (R:125)
CLK1:30.72MHz (R:384)
PLL1 PDF : 80kHz

1. use CLK0 and PLL1 and PLL2 locked and all output generated with sync toggling.
2. change input port to CLK1 with register setting change
PLL1/2 re-locked and output generated same frequency.

But "SYNC" toggling required after input port change?

Thank you.

Best Regards,
Jade

  • 0
    TI__Expert 8865 points
    Hi Jade,
    If I understood it right, customer is using Dual loop configuration(no 0-delay mode). When you switch the input clock from 10MHz to 30.72MHz, you are changing the PLL1 N&R dividers only. In this case, there is no need to apply the SYNC again.
    Best regards
    Puneet
  • 0 in reply to Puneet Sareen
    TI__Intellectual 1940 points
    Hi Puneet,

    If customer use 0-delay mode (Nested or Cascaded), SYNC event required?
    Even if Nested/Casceded 0-delay mode, there is no change in PLL2 R/N value.
    Thank you.

    Best Regards,
    Jade
  • 0 in reply to Jade Goo
    TI__Expert 8865 points
    Hi Jade
    As long as PLL2 dividers and output dividers are not changed, SYNC is not required again. Depends how nested 0-delay mode is implemented. If output divider is changed for the feedback channel in nested 0-delay mode (some configurations might need this) then that channel will go out of SYNC.
    Best regards
    Puneet