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LMK04828: Synchronous

Ljj Jason
Prodigy 110 points
Part Number: LMK04828


How to use LMK04828 in synchronousing multipieces ADC(such as four pieces of AD9625)?

Does an output single pulse signal works?If so , how to deal with the single pulse?

  • 0
    TI__Genius 9920 points

    Hi Jason,

    Yes. The single pulse on SYSREF could work. LMK04828 datasheet section "9.3.2.1.1 Setup of SYSREF Example" shows an example for 2 pulses SYSREF. It need DC coupling from LMK04828 to ADC. LMK04828's LVDS output type can match most of ADCs/DACs/FPGAs.

    LCPECL type is another option when LVDS can's match receiver spec. When we tune serial resistor R1 and bias resistor R2 for LCPECL, we can achieve different Vcm and Vod signal (|Voh-Vol|, single line swing) . For example, refer to below schematic,  when we select R2 = 162.5 Ohm, R1 = 57.4 Ohm, Rt = 50 Ohm,  we can get  VINH = 1.05V, VINL=0.65V, Vcm 0.85V.

    Hope it can help you.

    Regards,

    Shawn

  • 0 in reply to Shawn Han
    Prodigy 110 points

    Hi Shawn,

    Thank you!

    However, the most I want to kown is about how to use the single pulse to sythcronous,for instance,how to use multipieces devices to capture the edge(falling or rising) of the single pulse at the same time?

    The output SYSREF is actually DC coupling,furthermore,we use HMC7043 as the drive divider after LMK04828 to offer reference Clock for the sythcronousing devices as I said before.

    Looking forward to your help

    Best regards,

    Jason Ljj

  • 0 in reply to Ljj Jason
    TI__Genius 9920 points
    Hi Jason,
    This is a question for ADC/DAC how to process the SYSREF pulse.

    Regards,
    Shawn
  • 0 in reply to Shawn Han
    Prodigy 110 points

    Hi Shawn,

    You are right,

    Have you ever used SYSREF of LMK04828 to sythcronous devices?or the way、the devices etc related will be OK.

    much thanks!!

    Jason Ljj

  • 0 in reply to Ljj Jason
    TI__Genius 9920 points

    Hi Jason,

    You could learn JESD204B in ti.com.

    Regards,

    Shawn