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AM26LS32A: Termination resistor

Kazuki Itoh
Genius 9605 points
Part Number: AM26LS32A

Hi team,

I understand that AM26LS32A fail-safe doesn't work if the termination resistor is used.

Other than the fail-safe, is the device okay to be used with termination resistor?

My customers would like to know if it can cause damage or unexpected behavior.

Best regards,

Kazuki Itoh

  • +1
    Guru 267960 points

    The receiver will not be damaged (as long as you do not exceed the absolute maximum ratings).

    Without the fail-safe function, the output might be either high or low in case of a failure (open/short).

  • +1
    TI__Guru 50745 points

    Thanks Clemens!

    Hi Kazuki-san,

    This device is expected to be used with a termination resistor in order to suppress signal reflections on the signal line. Termination resistors should not significantly impact the ability for any fail-safe biasing functions to operate when implemented correctly. 

    External fail-safe biasing may be used in terminated systems in order to ensure receivers remain in a known output state in the case of an idle bus. Please see the application note linked below for more information on this practice. 
    https://www.ti.com/lit/an/slyt324/slyt324.pdf 

    The internal fail-safe biasing for AM26LS32A should also have no problem maintaining a known output when a terminated bus is idle. This bias applies internal to the receiver so that a 0V Vid will be registered as a valid high input. When termination is placed between the differential signal lines, an idle state will cause this 0V Vid allowing the internal fail-safe biasing to maintain this output-high condition. 

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott