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Original question:

SN65C1168: RS-485 compatibility

SN65C1168: RS-485 Compatibility

Kazuki Itoh
Genius 9955 points
Part Number: SN65C1168
Other Parts Discussed in Thread: THVD1520

Tool/software:

Hi team,

Could you let me know if SN65C1168 is compatible to RS-485?

It is not clearly mentioned on the datasheet.

I've already checked the previous thread, but it looks very old and some links to documents are expired.  

If not,  could you let me know if the device is applicable to half-duplex communication?

(Tieing pin#1&pin#13 and pin#2&pin#14 together and duing bi-directional communication)

Best regards,

Kazuki Itoh

  • +1
    Guru 283700 points

    A typical RS-422 load is 100 Ω; RS-485, 60 Ω. The SN65C1168 is specified only for the former.

    For two half-duplex channles, you should just use two RS-485 transceivers, e.g., 2× THVD1520.

  • 0 in reply to Clemens Ladisch
    TI__Genius 9955 points

    Hi Clemens-san,

    Thank you for the support.

    Could you check if the driver IC like SN65C1168 is able to do the single channel half-duplex birectional communication by tieing pin#1&pin#13 and pin#2&pin#14 together?

    Best regards,

    Kazuki Itoh

  • +1 in reply to Kazuki Itoh
    Guru 283700 points

    Yes, you can tie the driver and receiver pins together.

    But you should not use the typical RS-485 (2× 120 Ω) termination. If the termination resistors do not match the characteristic impedance of the cable, the achievable data rates will be reduced.

  • +1
    TI__Guru 60520 points

    Hi Kazuki,

    As Clemen's stated and the previous post you linked discussed, RS-485 devices can be used in place of RS-422.

    You can also tie a full deplex transceiver's cable side outputs and inputs together to make a half duplex set up.

    If you have additional questions, please let me know.

    -Bobby