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THVD1400: Non isolated version of ISO1430?

Thomas Lipps
Prodigy 30 points
Part Number: THVD1400
Other Parts Discussed in Thread: THVD1420, ISO1430

Hello support team,

I was looking for a counterpart of the ISO1430 without isolation. Comparing the datasheets of the ISO1430 and the THVD1420 made me assume that the bus sides are mostly identical.

Would the THVD1420 be the best fit for a RS485 network which should only be isolated at the remote locations (by ISO1430s ...)?
I would prefer the same signal behavior on all nodes regarding rise and fall times, amplitudes, distortions and so on ...

Best regards

Thomas

  • 0
    TI__Mastermind 45817 points

    Hi Thomas,

    The THVD1420 would be the best fit for a non-isolated ISO1430 - but there are a few caveats:

    VOD - the differential output voltage is going to be higher on the ISO device (typically) - both parts are RS-485 compliant however so they should be able to communicate with each other regardless if one device is outputting slightly higher VOD.

    Fault Protection: THVD1420 only allows up to +/-16V compared to ISO1430's +/-18V - while we do have more robust RS-485 devices they may start to differ on timing specifications more - so there isn't really an option that will preserve most of the parameters and protection voltage range.

    Timing - The transition times are similar - but the ISO devices prop delay is slower (which is going to be a theme - as the isolation barrier is going to add to the prop delay time).

    Besides that this is probably the closest device to the ISO1430 that is not isolated. That being said - if any of these caveats are unacceptable for the system itself please let me know if you have any tight timing requirements that need to be met to see if we may have something a little more robust - but the 1420 is the closet. 

    Best,

    Parker Dodson