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Original question:

TMDS442 / floating TMDS input

TMDS442: unused input terminal

Yasushi Fujiwara
Genius 12725 points
Part Number: TMDS442

Hello experts,

Regarding an answer of a following thread, would you clarify what is different between unused input terminal and left open (it has unconnected connector)? I suppose it seems there are same condition.

https://e2e.ti.com/support/interface/f/138/t/333657?tisearch=e2e-sitesearch&keymatch=TMDS442

Best Regards,
Fujiwara

  • 0
    TI__Guru**** 176121 points

    Fujiwara-san

    Unconnected connector means TMDS422 input is connected to the the connector, but there is no cable attached at the connector.

    Unused input terminal means TMDS422 input is floating, not connected at all.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    TI__Genius 12725 points

    David-san,

    Customer wants to left open (floating) the unused input terminals. The datasheet stated that "An unused input channel can be externally biased to prevent output oscillation". If customer left open the unused input terminals, TMDS output will oscillate? I want to know an external biasing for unused input terminal is just recommendation or it is mandatory. Which is TI suggestion?

    Best Regards,
    Fujiwara

  • 0 in reply to Yasushi Fujiwara
    TI__Guru**** 176121 points

    Fujwara-san

    I would recommend following the datasheet. Since TMDS input pins are not failsafe circuits. The complementary input pin is recommended to be grounded through a 1-kΩ resistor and the other pin left open.

    Thanks

    David