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LMK04832: multi-device SYNC

new2day
Expert 1950 points
Part Number: LMK04832
Other Parts Discussed in Thread: LMK04828

Tool/software:

We have a LMK04832 on the board and like to get all clock outputs aligned between LMK04832 (or boards). 

1. LMK04832 can be in single loop  or single loop 0-delay mode.

2. CLKin1 is used as REF IN (not OSCin). 

3. The phase aligned 100MHz reference clock and SYNC signals (aligned) are provided to each LMK04832 or board. 

4. SYSREF outputs are continuous and programmable. 

5. DCLK outputs are programmable. 

see attached TICS Pro settings. 

Question #1

Which one is better to get multiple LMK04832, 0-delay or not?

Question #2

Is SYNC signal (pin) required? in these two modes? 

Question #3

I could not get the outputs aligned all the time.

Any suggestions? Thank you. 

pll_sync_settings.pdf

  • 0
    TI__Genius 10995 points

    Hello new2day,

    To clarify, CLKin1 is never used as OSCin. CLKin1 and OSCin are different pins on the LMK04832.

    new2day said:
    Which one is better to get multiple LMK04832, 0-delay or not?

    0-delay aligns your inputs to your outputs, so for complete synchronization across the device, 0-delay is recommended. Note that is not required, this word document will give you more information in synchronizing the LMK04828 which is a very similar part ot the LMK04832.

    new2day said:
    Is SYNC signal (pin) required? in these two modes? 

    A SYNC signal is required, however, that could come internally from the LMK04832 or could be external and introduced via the SYNC pin. Whether using 0-delay or no 0-delay, the SYNC is required to align the outputs of one LMK04832 and align all the other LMK04832s.

    new2day said:

    I could not get the outputs aligned all the time.

    Any suggestions? Thank you. 

    Please follow section 8.3.3.1.1 Setup of SYSREF Example on the data sheet (p. 31). The document I linked above also comments high level about SYNCing devices and outputs.

    Best,

    Andrea