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Original question:

DS90UB953-Q1: Power Over Twisted Pair

SN65HVD63: Can this be adapted for a twisted pair operation (not coax)?

Lauren Mayfield
Expert 6910 points
Part Number: SN65HVD63

Hi INT team,

Can this part be adapted for a twisted pair operation?

From figure 24 in the datasheet there is a reference to twisted pair operation, could you explain this figure in more detail?

Is there app notes or more material that explain how to adapt this part for a twisted pair operation?

Thanks,

Lauren

  • 0
    TI__Guru 62910 points

    Hi Lauren,

    The twisted pair mention in the datasheet actually refers to transmission using RS-485, another physical layer supported for AISG interfaces.  You could send the OOK signaling of the SN65HVD63 over whatever you would like, though, you would just want to make sure that the media used can support the carrier frequency (i.e., insertion loss isn't too high such that the end-of-line signal remains above the receiver sensitivity level).  The OOK output is single-ended (ground referenced), so you could use the complementary wire in the twisted pair to carry a ground or you could use a balun to convert the OOK signaling to a balanced differential signal.

    Regards,
    Max

  • 0 in reply to Max Robertson
    TI__Expert 6910 points

    Hi Max,

    Awesome, thank you for your response!

    One more follow up question, I would like to try coupling it onto a DC supply rail - how would you recommend going about that?

  • 0 in reply to Lauren Mayfield
    TI__Guru 62910 points

    Lauren,

    This can be accomplished via a "bias-tee" structure.  That is, the high-frequency OOK signalling could be coupled to/decoupled from the line via a series capacitance, while the DC power can couple/decouple via a series inductance.  This makes the power circuitry high impedance at the OOK carrier frequency so that it does not load the high-frequency signaling and cause distortion or loss of data.  Similarly, the inductance would effectively block the OOK signals from making it onto the power rail and introducing noise into the system.  The capacitors would block the DC signal from being seen by the OOK receiver as well and allow it to continue to operate within its normal voltage range.  Please let me know if this isn't clear.

    Regards,
    Max