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SN65HVD75DGKR Half-Duplex RS-485 Transceiver

Daniel Schuman
Prodigy 20 points

Does this device meet the requirement in the RS-485 Standards that a driver that is powered-down should sink no more than 100 microamps?

Daniel Schuman

Emerson Process Management

  • 0
    TI__Guru 63030 points
    Hi Daniel ,

    I will move your post into appropriate forum.
  • 0 in reply to ShreyasRao
    TI__Guru 62920 points

    Hi Daniel,

    Are you referring to the input current into the bus?  If so, the RS-485 specification allows for higher currents than 100 uA.  The I/V characteristics of a standard "unit load" are shown below:

    This gives the amount of current an inactive transceiver (either powered or unpowered) can sink as a function of applied voltage.  An RS-485 bus can support up to 32 of these "unit loads."  The HVD75 device has input leakage currents lower than the standard (150 uA at 12 V), and so they are said to be "3/20 unit load" transceivers.  This means that as many as 213 can be placed on a bus without violating the standard loading conditions.

    I hope this answers your question; please let me know if I am missing something.

    Regards,
    Max