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SN65LBC176: Vod of SN65LBC176

Xiaoying Lu
Expert 4270 points
Part Number: SN65LBC176

Hi team,

Can I know why the min differential output voltage of SN65LBC176 is only 1.1V when RL=54ohm? Seems that the RS-485 standard is >1.5V?

Regards,

Xiaoying

  • 0
    Guru 316510 points

    Section 4 says:

    These transceivers are suitable for ANSI Standard TIA/EIA−485 (RS-485) and ISO 8482 applications to the extent that they are specified in the operating conditions and characteristics section of this data sheet. Certain limits contained in TIA/EIA−485−A and ISO 8482:1987 (E) are not met or cannot be tested over the entire military temperature range.

    I suspect this device was originally designed for unidirectional or full-duplex (RS-422) applications with only one termination resistor.

  • +1
    TI__Guru 52062 points

    Hi Xiaoying,

    Clemens is correct - this part doesn't meet the full RS-485 standard across the entire operating range and while I am not 100% sure why the design was made this way it could be for a few reasons - but ultimately it does meet the full range. The higher temps allowed by the "65" and "55" variants of the device can cause a degradation below RS-485 standard - that is why the "75" device can meet the specs. 

    So in general - while we don't guarantee it on the "65" variant - you should be at RS-485 spec between 0C to 70C (as the "75" and "65" should work very similarly between 0C and 70C) - but beyond that its more likely there could be degradation. 

    Please let me know if you have any other questions!

    Best,

    Parker Dodson