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TMUX1219: Leaving S2 pin floating

Oba
Genius 16135 points
Part Number: TMUX1219
Other Parts Discussed in Thread: TUSB320, SN74LVC2G07

Hello,

I have a question for TMUX1219.

The below is the block diagram that I’m thinking now.
AM335x USBx_ID pin have to be connected to GND (less than 10 ohm) if it is “device mode” and have to be floating(over 100KOhm) if it is “host mode”.
Then I’m considering to use TMUX1219 to switch GND and floating.
I couldn’t find any good low cost 1:1 SPST device less than Rds_ON=10Ohm. This is the reason for TMUX1219.

My question is that is this configuration leaving S2 pin just floating allowed ?

 

Regards,
Oba

  • 0
    TI__Mastermind 46427 points

    Hi Oba,

    Leaving S2 floating in this application is fine.

    One note to mention about the application:

    At a 5V supply the max rated on resistance across the rated temperature range is always < than 10 Ohms.

    At 3.3V supply the max rated on resistance across the rated temperature range can be > 10 Ohms - but they are edge cases and are more rare; but we can't guarantee at 3.3V it will always be below 10 Ohms.

    Below 3.3V for supply and the on resistance will be > 10 Ohms.

    If you have any other questions please let me know!

    Best,

    Parker Dodson

  • 0
    Guru 271320 points

    The USBx_ID pins are designed for open-drain signals, so I suspect that connecting the TUSB320's ID output directly would just work.

    Anyway, if you want a lower output impedance, you could also use an open-drain buffer such as the SN74LVC2G07 (two outputs in parallel to get lower output impedance).