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ADC12J4000 - How to configure DC Coupled SYSREF

Hiroshi Katsunaga
Mastermind 6480 points
Other Parts Discussed in Thread: ADC12J4000, LMK04828

Hello,

My customer has a question about ADC12J4000.

[Q1]

Please tell me how to configure DC Coupled SYSREF between LMK04828 and ADC12J4000.

Is my understanding correct ?

<My understanding>

  • Set the SYSREF output in LMK04828 "LVPECL 1600mV"
  • connected directly between SYSREF output in LMK04828 and SYSREF input in ADC12J4000.
  • Set "DC_LVPECL_SYSREF_en" bit in ADC12J4000 "1"

Best Regards,

Hiroshi Katsunaga

  • 0
    TI__Mastermind 44680 points

    Hi Hiroshi

    For DC-coupled SYSREF from the LMK04828 to the ADC12J4000 I recommend the following setup.

    • Connect the LMK04828 SYSREF output to the ADC12J4000 SYSREF input using the following circuit configuration:

    The series termination resistors work in combination with the ADC12J4000 internal terminations to provide the proper common mode and differential voltages needed.

    • Configure the LMK04828 SYSREF output for the ADC to LCPECL mode. This has a lower common mode voltage than standard LVPECL, so it aligns better with the ADC12J4000 SYSREF common mode input requirements.
    • Configure the ADC12J4000 SYSREF receiver to DC coupled LVPECL mode by setting the DC_LVPECL_SYSREF_en bit.

    Please let me know if you have additional questions.

    Best regards,

    Jim B

  • 0 in reply to Jim Brinkhurst1
    Mastermind 6480 points
    Hi Jim,

    Thank you for your fast response.
    I understood your all comments.

    Thank you for your cooperation.

    Best Regards,
    Hiroshi Katsunaga