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THVD1406: Auto-direction control in my understanding

Shunsuke Yamamoto
Expert 8701 points
Part Number: THVD1406
Other Parts Discussed in Thread: THVD1505

Hi team,

Auto-direction control of RS485 transciever can detect if the Inverted polarity is connected to the RS485 transceiver. Is my understanding correct?

For example, A pin of THVD1406 is connected to B pin of another THVD1406, but it works.

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Best regards,

Shunsuke Yamamoto

  • 0
    TI__Genius 16642 points

    Yamamoto-san,

    Auto-direction and bus polarity correction are two different, special features for RS-485 transceivers. 

    THVD1406 has auto-direction control where the transceiver can switch between driving and receiving automatically without dedicated control pins. This is different from what you are describing above. This function is detailed in full here:

    https://www.ti.com/lit/an/slla574/slla574.pdf 

    What you are describing is found in the THVD1505, where it will detect if the A and B bus pins are properly connected. More information on how to setup this device can be found here:

    https://www.ti.com/lit/an/slla572/slla572.pdf 

    Let us know if you have any other questions!

    Best,

    Ethan

  • 0 in reply to Ethan Sempsrott
    TI__Expert 8701 points

    Hi Ethan-san,

    Thank you so much for clarifying the difference between auto-direction control and bus polarity correction!

    By the way, are there any half-duplex RS485 transceivers which auto-direction control and bus polarity correction are integrated into?

    Best regards,

    Shunsuke Yamamoto

  • 0 in reply to Shunsuke Yamamoto
    TI__Genius 16642 points

    Yamamoto-san,

    Not currently. However, the THVD1505 (polarity correction) can be setup with DE and /RE connected together so only one control input is necessary to change from driving/receiving (instead of one for each function). 

    If there is strong interest for a combined polarity correction and auto-direction control receiver, please reach out to Rosemary Sanchez on our RS-485 marketing team.

    Best,

    Ethan