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TMUX1574: Are Sx pin output state fixed during power-on and power-down?

Hisao Uchikoshi
Genius 14900 points
Part Number: TMUX1574
Other Parts Discussed in Thread: TMUX1511

Hi Experts,

My customer is using Dx pins are pull-up. During power-on and power-down, because logic pin(EN and SEL pin) are pull-down internally, can we consider that the internal switch is always ON state and SxA pins are not in Hi-Z state? How about SxB pins?

I also want to know the meaning of "four external components". If logic pin stand for EN pin and SEL pin, it should be two external components.

Could you please explain?

Regards,

Uchikoshi

  • 0
    TI__Guru 52392 points

    Hi Hisao,

    There is a weak pull-down, in most applications you can assume the IC will start as you stated above. If there is a relatively large current being injected into the select pin this could cause the logic state to become undefined. If this is a concern an external pulldown can be added to increase the strength of the pull-down at the cost of more power consumption.

    When the SEL and /EN are at logic state 0, SxB will be in a high-Z mode. 

    The "up to four external components" is a generalized statement that is in all of our devices that have integrated resistors because some parts such as the TMUX1511 have four select pins. However for the the 1574 you are correct there is only 2 integrated devices. 

    If you have any other questions please let me know!

    Best,

    Parker Dodson