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THVD1450: Is my implementation with the selected TI RS485 transceptor correct?

Martin Holguin
Intellectual 340 points
Part Number: THVD1450
Other Parts Discussed in Thread: THVD1426, THVD1406

Tool/software:

I’ve been reading some literature about the RS-485 interface and how to design a functional circuit with ESD protection. Is the design I’m proposing below correct? Can I expect it to work properly on my PCB?

  • 0
    TI__Guru 72901 points

    Hi Martin,

    What exactly are you trying to do with the DE/RE circuit tied to Tx?

    My guess is you are trying to make the bus drive in one direction and passively (with the resistors to GND and Vcc) drive in the other direction to avoid contention.

    The problem with this is the enable and disable time of RS485 devices are not uniform and when you attempt this at high speeds, the bit distortions will be too large that you get framing errors.

    -Bobby

  • 0
    Guru 316760 points

    If you do not have a separate direction signal, use a transceiver with the auto-direction feature like the THVD1406/THVD1426.