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SN75ALS181: Is SN75ALS181 supporting internal FailSafe function?

Rick Chen1
Prodigy 10 points
Part Number: SN75ALS181

Hi,

I have question about RS485 Tranceiver SN75ALS181.

Is SN75ALS181 supporting internal FailSafe function?

I can't find the word "Open Failsafe" in the datasheet of SN75ALS181.

So, I'm guessing that SN75ALS181 aren't supporting interal failsafe. Am I wrong?

best regards,
Rick Chen

  • 0
    TI__Guru 62920 points

    Hi Rick,

    There is a very weak positive differential bias introduced on the inputs - this is shown in the input equivalent schematic diagram as a 288-kOhm pull-up on A and pull-down on B.  This may be too weak to reliably implement a failsafe function, particularly if the bus remains terminated.  So, users could implement failsafe biasing externally if this is a concern.

    Regards,
    Max