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probe LVDS signal

Xiang Chao
Intellectual 360 points


On my board, SN74LVDS31 is used to convert a single-ended clock signal (50MHz) to LVDS differential clocl which then feed a DSP(6474) as main cloclk (AC coupled).

With proper 3.3V power supply and enable signal (G=1 and /G=float), I can proble the colck signal with oscilloscope on pin 1, but no signal found on pin 2 and 3, which should be the + and - of LVDS out put.

The + and - side of LVDS signal can be displayed with normal osscilloscope probe? Or should I use a differential probe?

Thx

  

  • 0
    TI__Mastermind 24985 points
    Hello,

    Typically it is best to use a differential probe for differential signalling, as it will not have to be relative to ground.
    It is possible that it could be displayed with a normal scope probe, however, the scope typically has a shared ground, so you need to make sure that you dont connect the ground of one probe to a different point from the ground of another probe or else you may be shorting two points with different potentials.

    Best,
    Michael