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Original question:

AM26C32: Reliable fail-safe

AM26C32: Fail-Safe

Yuta Nishie
Genius 4125 points
Part Number: AM26C32

Tool/software:

Hi,

Regarding the fail-safe function, the following thread states that it works in idle and open states.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1202401/am26c32-reliable-fail-safe?tisearch=e2e-sitesearch&keymatch=AM26C32%2520fail#

Is it correct to assume that the fail-safe function works even if the differential input terminal is short-circuited? Or do I need to add a circuit for short-circuit protection?

Best Regards,

Nishie

  • 0
    Guru 296830 points

    The description in the datasheet is not very precise; it does not say what "idle" means.

    As shown in the functional block diagram, the A/B inputs have weak pull-up/-down resistors. This implies that the termination resistors would short the inputs, and that the fail-safe does not work for an idle+terminated or shorted bus.

  • 0 in reply to Clemens Ladisch
    Genius 4125 points

    Hi Clemens-san,

    Let me check if I understand your answer correctly.

    ・The AM26C32 failsafe function works only when the circuit is open.

    ・The failsafe function does not work when the circuit is idle or short. If protection is required, an external circuit must be added.

    Best Regards,

    Nishie

  • +1 in reply to Yuta Nishie
    Guru 296830 points

    Correct.

    Devices that have fail-safe receivers for open, idle, and shorts mention this explicitly in their datasheet. All modern transceivers have this, but they are one-channel devices.

  • 0 in reply to Yuta Nishie
    TI__Mastermind 48297 points

    Hi Nishie,

    Clemens is correct - please let me know if you need any other help!

    Best,

    Parker Dodson