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LMX2694-EP: SYNC could be multiple of pulses?

Kazuhiko Hirano
Genius 14968 points
Part Number: LMX2694-EP

Hello,

Even if SYNC (SYNC category is 2) is multiple time of pulses (for example ten pulses) and pulse interval is <t1 in the datasheet Fig7-3, the last pulse is finally valid and the RFOUT phase is deterministic to OSCIN?
Or SYNC has to be only one pulse? If so, my customer needs to modify their PCB design, though.

Best regards,

K.Hirano

  • 0
    TI__Guru** 107190 points

    Hi Hirano-san,

    For Cat.2 sync, the timing of the SYNC signal is not critical, so we can simply pull SYNC pin HIGH to trigger phase synchronization. 

  • 0 in reply to Noel Fung
    TI__Genius 14968 points

    Noel,

    I know that. And I already recommended that to my customer.
    But, at my customer's design, multiple LMX2694s are driven by multiple pulses of SYNC already to align all RFOUTs.
    If possible, they would like to stay the current design and would not like to modify anything.
    So, if you could answer to their first specific question, it would be very appreciated.

    Best regards,

    K.Hirano

  • 0 in reply to Kazuhiko Hirano
    TI__Guru** 107190 points

    Hi Hirano-san,

    Does the customer has individual SYNC for each LMX2694?

    Usually, all LMX2694's SYNC pin are connected together, a single SYNC signal rising edge can trigger phase synchronization for all LMX devices.

    If your question was, instead of one SYNC rising edge, can LMX device accepts multiple SYNC rising edge? The answer is, every rising edge will trigger a synchronization process. For example, if you send six SYNC pulses, LMX device will perform synchronization six times. 

  • 0 in reply to Noel Fung
    TI__Genius 14968 points

    Noel,

    My customer 1 to 8 clock buffer to distribute multiple SYNCs to multiple LMX2694s.
    And SYNC is not one pulse, multiple pulses somehow.
    They would like to confirm if the last SYNC pulse can really work correctly and previous pulses do not provide any wrong side effects about the deterministic RFOUT phase.

    Best regards,

    K.Hirano

  • +1 in reply to Kazuhiko Hirano
    TI__Guru** 107190 points

    Hi Hirano-san,

    Like I said in the previous post, if you send six SYNC pulses, the LMX device will perform synchronization six times. There should be not difference in synchronization result between the first and the sixth synchronization.

  • 0 in reply to Noel Fung
    TI__Genius 14968 points

    Noel,

    Thank you for your confirmation.

    Best regards,

    K.Hirano