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SDI Receiver- Minimum input swing and cable length

Madhu Sharma
Expert 2915 points
Other Parts Discussed in Thread: LMH0344

Hi,

In the SDI Adaptive Cable Equalizer IC(LMH0344), in the input characteristics, it is mentioned that a minimum of 720 mV swing is required. In the bottom note, it is also mentioned that this specification is only for 1m cable. So please let me know how this minimum required swing depends upon cable length.

Thanks & Regards
Madhu Sharma K

  • 0
    TI__Mastermind 29655 points

    Hi Madhu,

    The specification in the datasheet is taken directly from compliance standard requirements from SMPTE Standard ST424 (previously called 424M).

    In this standard, the following is required:

    Since the definition in 6.1.1 is described through a 1-m cable, we have added the note that the measurement is taken through 1-m of cable to show compliance. The source going into your LMH0344 should be at least 720 mV amplitude when measured after 1-m of cable. 

    It is expected that after a long amount of cable length, the effects of jitter will begin to close the eye, and the LMH0344 will attempt to improve the eye quality by automatic cable equalization. The maximum amount of cable length that can be equalized is dependent on the quality of the cable you are using.

    The Mute Reference can be used as a way to limit the cable length that the LMH0344 will equalize before going into mute.

    Thanks,

    Michael