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SN7534051: Input signal termination

Mo Abdol
Prodigy 80 points
Part Number: SN7534051

I have two systems that need access to the same RS422 signal source. So, I wish to split the RS422 signal (running at a maximum of 5 MHz) into two (2) branches, and feed each branch to a different system. I have selected the SN7534051 chip. I am looking for a simple circuit diagram that shows if and how the inputs to the SN7534051 should be terminated. Also, I need to know if the outputs need any form signal management, or can they just be connected directly to the destination device?

Thanks,

Mo

  • 0
    TI__Guru 62920 points
    Hi Mo,

    In general, RS-422 signals are typically terminated at the furthest end of the transmission cable using a shunt resistance between the two lines making up the balanced differential pair. The resistance is typically chosen so that it matches the differential characteristic impedance of the cabling, which in many applications is in the 100-120 Ohms range.

    The RS-422 outputs can be connected directly to the destination device, and termination can again be placed at the end of that connection.

    This link is unidirectional (data only travelling one way), right? If not, then you may need some additional logic to control the direction of data flow. An example implementation is shown in this reference design: www.ti.com/.../TIDA-01365.

    Please let us know if you have any further questions or if I've misinterpreted what you are trying to implement.

    Regards,
    Max