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TMUX136: TMUX136 Com1/2 connection

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?



  • 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.

  • 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.