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TMUX136: TMUX136 Com1/2 connection

Mark Chen52
Expert 7225 points
Part Number: TMUX136

Hi Expert,

I saw this device no need external pull up resistor for design, but I still would to double check with you for below question: 

If customer send signal from  COM1/2 to A/B port, does it need pull up resistor on COM1/2 ?  

if no COM1/2, just to pull down with 50 ohm, right?

Regards,

Mark

  • 0
    Guru 298810 points

    The analog switch itself does not care about the signals passing through it. If your circuit needs to see a high voltage when the signal is floating or disconnected, then your circuit needs a pull-up resistor.

    A 50 Ω pull-down is recommended only when the other channel carries very-high-frequency signals. Otherwise, you can leave it floating.

  • 0
    TI__Genius 10974 points

    Hi Mark,

    This will actually depend on the protocol you are using. For example, if you are using I2C that requires pullup resistors for proper operation, you would need to put a pullup on both the input and output ports of the multiplexer/switch (to make sure that in the case of the switching being disconnected, the attached devices still have a pullup). However, if your application does not require it, then there is obviously no need to put any as there is no requirement needed by the multiplexer/switch.

    Lastly, if you are using a higher frequency application, then it is advised to tie the unused channels to GND through a 50 ohm resistor.

    Thanks!

    Bryan