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LMK01000: Non-clocking application: SE-to-LVDS translator

Ryan.Bishop
Expert 3900 points
Part Number: LMK01000
Other Parts Discussed in Thread: LMK01801

Hello,

I am looking for a part to do SE-to-LVDS translation with ultra-low skew. Our dedicated LVDS drivers couldn't reach the accuracy we need, so we are considering clock buffers for this application.

  1. Is it safe to assume that our highest frequency parts will have the lowest skew?
  2. We are hoping to get <1ps. This part has 4ps typical, 30ps max. Are there any parts that would outperform the LMK01000 for this purpose?

Thank you!

Regards,
Ryan B.

  • 0
    TI__Mastermind 28540 points

    Hello Ryan,

    I wouldn't consider <1 ps as realistic.

    In general I'd consider higher frequency parts to be better.

    You may take a look at LMK01801, however it doesn't have max numbers.

    73,
    Timothy

  • 0 in reply to Timothy T
    TI__Expert 3900 points

    Hi Timothy,

    Thanks for your help on this. I had a quick follow up question if you don't mind:

    Will this work at DC? By that, I mean we will be sending a pulse every 30s or so (as opposed to a very regular periodic pulse train).

    Will there be any issues using the part like this?

    Regards,
    Ryan B.

  • 0 in reply to Ryan.Bishop
    TI__Mastermind 28540 points

    Hello Ryan,

    The LMK01801 is a better candidate there.  LMK01801 does support a CMOS input buffer mode (CLKinX_BUF_TYPE = 1) which allows you to drive the LMK01801 DC coupled with an LVCMOS signal.

    The LMK01000 has a bipolar input which we specify in the datasheet to be AC coupled to the external signal.  Accordingly you wouldn't be able to use this at DC.  Technically if your input signal reasonably matched the self-biased common mode on the device side - you could also DC couple, but that would be outside of our recommended operating conditions.

    73,
    Timothy

  • 0 in reply to Timothy T
    TI__Expert 3900 points

    Hi Timothy,

    Thanks for guiding me to the right part. It seems like LMK01801 is indeed the best option.

    Just to make sure I understand completely, I've included a rough drawing of how we want to use the part. I wasn't sure if the device needs a consistent input frequency to operate properly (which won't be the case here)

    TOP: typical application

    BOT: our applications (could be 30s between pulses)

    Thanks!

    Regards,
    Ryan B.

  • 0 in reply to Ryan.Bishop
    TI__Mastermind 28540 points

    Hello Ryan,

    I don't see an issue with this operating as described, however I notice that the datasheet doesn't explicitly say DC operation.  In the MOS with a CMOS input, I don't see an issue with DC.

    I'll check to see if we can add this.

    73,
    Timothy