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LMH1218: What to do with unused Input/Output?

Robert Steigemann
Prodigy 40 points
Part Number: LMH1218


Hi @ All,

We're going to use the LMH1218 in one of our camera designs. We want to use IN0(+/-) and OUT0 for 75Ohm SDI output.

After considering the datasheet I'm unsure what to to with the unused input IN1(+/-) and output OUT1(+/-). I would leave the output open (unconnected) and disable it (Reg_0x31[1:0] = 0b01). Should I connect the unused input (Pin 8, 9) to GND, or are they internally biased to a proper DC-level because of the required AC-coupling?

Any advise would be nice.

Best,

Robert

  • 0
    TI__Mastermind 29655 points

    Hi Robert,

    For the unused input, the channel is automatically powered down when it is not selected by the 2:1 input mux. You can therefore leave these unused pins floating. The same can be said for the unused output, except you will need to ensure that you disable the output through register control (which you have already found).

    Alternatively, if you wish to terminate the unused pins to GND, there is a way to do this accordingly in the following post: e2e.ti.com/.../519791

    Thanks,

    Michael