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THVD1454: Hysteresis vs positive and negative-going thresholds

Michael Biggs
Prodigy 10 points
Part Number: THVD1454

Tool/software:

I'm looking at a few RS-485 transceivers, and one parameter of interest is the hysteresis. I would expect the typical hysteresis to be equal to the difference between the typical positive-going threshold and the typical negative-going threshold, but in the THVD1454 datasheet we have -85mV  and -150mV for a difference of 65mV, but the typical hysteresis is listed as 50mV. Is there something else affecting the hysteresis? Or is one of the typical numbers wrong?

  • +1
    TI__Genius 13732 points

    Hi Michael,

    Thanks for reaching out about THVD1454 on E2E!

    The values are indeed correct. Since we do not specify a max hysteresis, it is possible to have it at 65mV. Additionally, -85mV and -150mV are just typical values and can be slightly off. TI only guarantees the MIN and MAX values. 

    I checked our simulation and test data, and the VTH- is closer to -135mV. So this still puts the hysteresis around 50mV either way.

    Let me know if that answers your question!

    -Ethan 

  • 0 in reply to Ethan Sempsrott
    Prodigy 10 points

    Thanks for the test data info. I understand that "typical" is just that, but it's comforting to have the numbers all add up, which they do using -135mV.