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SN65LVDS9638: Is there an RS422 drop in replacement for this part?

Chris Dehmelt
Prodigy 30 points
Part Number: SN65LVDS9638
Other Parts Discussed in Thread: UA9638C-EP, THVD1450, AM26LV31E

Is there an RS422 drop in replacement for this driver (that will operate over temperature)?

  • 0
    TI__Guru*** 146785 points

    not sure your question, there is  no relationship between LVDS and RS422.

  • 0 in reply to Brian Zhou
    Prodigy 30 points

    Brian:

    I have an existing design  that uses the LVDS part; I have a new requirement that needs differential/RS422 or RS485 signaling, so I'm looking for a part that has the same footprint, pin layout, so I can just drop it into the design without respinning the board ($) or cut and jumpering a part in.  Part must also be industrial temp grade.

  • 0 in reply to Chris Dehmelt
    TI__Guru*** 146785 points

    change to INT-TRX group, they may have solution

  • 0 in reply to Brian Zhou
    TI__Guru 62920 points

    Hi Chris,

    The uA9638C-EP device is a dual RS-422 driver with equivalent pinout and temperature rating from -40 C to +85 C.  It sounds like this is what you are looking for.  Please let me know if you have any feedback on it.

    Regards,
    Max

  • 0 in reply to Miguel Robertson
    Prodigy 30 points

    Hi Max,

    It may..., however, I downloaded the uA datasheet and it notes that the part requires Vcc of 5V (in the recommended ratings table), whereas the SN part requires Vcc of 3.3V.   BUT, the absolute maximum table indicates that the part can run with a Vcc of anywhere from .5V to 7V, so sounds like it should work...

    Thoughts?

    Thanks,

    Chris

  • 0 in reply to Chris Dehmelt
    TI__Guru 62920 points

    Chris,

    I wouldn't advise running this part at VCC = 3.3 V; it may be functional, but I would not expect it to meet RS-422 requirements (particularly for specifications like the differential output amplitude under standard loading conditions).  If the VCC cannot be raised (for example, due to being shared by other components), I'm afraid there is no direct drop-in option available.

    For options at 3.3 V, you could take a look at AM26LV31E.  This is a quad-channel device, so you would need to waste a couple of channels - this is OK from a device perspective (just tie the driver logic input high or low and leave the Y/Z outputs floating) but may be undesirable for you in terms of space.  We also have a single-channel THVD1450 that could work, but you would need two of them (and you would in that case have two unused receive channels).

    Regards,
    Max