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SCAN921226H: Bus LVDS Serial Output Rated for 27ohm Load.

Daniel Xie
Prodigy 75 points

Part Number: SCAN921226H

What dose this 27ohm load mean?

Can you please explain the difference between the 27ohm load and the 100ohm terminal resistance? Thanks.

  • 0
    TI__Guru**** 193391 points

    Daniel

    Bus LVDS drives multi-drop or multi-point application. While the typical termination impedance is 100 ohm, but with multiple drivers or receivers, the additional loading due to these extra driver/receivers will result in an effective impedance of considerably less than 100 ohm.

    Thanks

    David 

  • 0 in reply to David (ASIC) Liu
    Prodigy 75 points

    Thanks for your info.

    If the Bus LVDS drives point-point application, the typical termination impedance should be 100 ohm and the typical differential voltage should be 350 mV, right?

  • 0 in reply to David (ASIC) Liu
    Prodigy 75 points

    Can you answer me another question? I want to put a common mode choke on the lvds data lines. How does the differential mode impedance of the choke affect the differential voltage margin of the receiving end?  Should I do a voltage divider to calculate the margin? Thanks.

  • 0 in reply to Daniel Xie
    TI__Guru**** 193391 points

    Daniel

    For point-point application, the typical termination impedance is 100ohm and differential voltage swing of 350mV.

    For calculate the margin, it is better to run a simulation to calculate the differential voltage margin since the amount of margin also depends on the data rate, cable insertion loss, etc. 

    Thanks

    David