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Original question:

66AK2G12: checking the schematic

66AK2G12: Optional LVDS Clock Inputs Not Used

Naoki Kawada
Guru 19890 points
Part Number: 66AK2G12

Hi,

My customer forgot to apply the following directions for some differential clock inputs on their custom board:

5.9.3.2 Optional LVDS Clock Inputs Not Used

Some *_P/N signals are pulled up/down with 10kΩ rather than 130Ω. I know the recommendation is still following the datasheet, but just in case, i would like to confirm that, is there any possibilities to have fatal problem in the device point of view if they leave the current connection ? Can you share the reason for using 130Ω?

Best Regards,
NK

  • 0
    TI__Genius 17510 points

    Hi,

    I don't know the reason for the 130-ohm value.I mean , there might be, I didn't check internally for now.

    With the 100-ohm internal termination and 3.3V, this would give ~1V difference on P vs N inputs, while for LVDS it can be much smaller (few tens of mV).  The bad thing here is the wasted ~10mA for a feature you don't even use. I think this document explains pretty good how to deal with unused LVDS inputs:

    Regards,

    Stan