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THVD4421: Are RS-232 functions disabled and High-Z when in RS-485 mode?

Mark Hall
Prodigy 140 points
Part Number: THVD4421

Tool/software:

The data sheet clearly says "When the device is configured in RS-232 mode, RS-485 circuits and 120Ω termination are disabled and do not interfere in RS-232 communication."

But says nothing like this for RS-485 mode?

i.e. There is no statement: "When in RS-485 mode, are the RS-232 circuits disabled and do not interfere in RS-485 communication"

Seems this would be the case since pin L2 is shared between the RS-232 <> RS-485.

  • 0
    TI__Genius 13752 points

    Hi Mark,

    Thanks for reaching out!

    Right after that sentence, the datasheet mentions that in RS-485 mode, the RS-232 charge pumps are off and the 5K load resistors are disabled. This prevents any RS-232 signal from being generated onto the bus, which means that RS-232 functions are indeed disabled. 

    Let me know if that answers your question, or if you still have further questions,

    -Ethan

  • 0 in reply to Ethan Sempsrott
    Prodigy 140 points

    Thanks Ethan - I saw that statement - and since it specifically is directed at the 'bus', I just was concerned about the "L-side".

    But since L2 is shared with both RS-485 & RS-232 receiver, it implies that the RS-232 receiver is disabled when in RS-485 and vice-versa.

    Consider issue resolved.