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DS26LV32AT: Input pins recommended connection for unused channel.

Part Number: DS26LV32AT
Other Parts Discussed in Thread: AM26LV32

Hello team,

I'd like to know what is the best recommended connection(OPEN/VCC/GND) for unused channel for the following devices.
1) DS26LV32AT
2) AM26LV32

It is sometimes confusing to me how we should consider it with internal fail safe function.
Any advice of the application expert is really appreciated.

Thanks in advance.
S.Sawamoto

  • Hello Sawamoto-san,

    For both devices, an unused input channel can be left disconnected.  Under this condition, the corresponding output for that channel will be at a high logic level.  This output can be left disconnected as well.

    Note that this would make use of the internal failsafe function, which detects the loss of an input signal.  If the device were operated in an application that is expected to have a large degree of noise coupling onto the unused port (i.e., high enough that the coupled noise could be detected as a valid RS-422/485 input signal), then you could improve noise immunity and prevent output toggling by using an external biasing network (A pulled high, B pulled low).  However, this is rarely needed and the consequences of an unused output port toggling are minor, so in the majority of cases leaving the unused channel disconnected is the simplest option.

    Regards,
    Max