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TUSB322I: Some questions of TUSB322I (Dir pin operation, EN_N treatment, INT_N, ID pins pull-up resister value)

Motoyasu Hattori
Genius 11095 points
Part Number: TUSB322I

Hi,

We have some questions related with TUSB322I.

  • DIR pin operation.

Datasheet said "DIR of plug. The open drain output indicates the detected plug orientation: Type-C plug position 2 (H); Type-C plug position 1 (L)."   If TUSB322I detects CC2 position, TUSB322I outputs open on DIR pin, but High due to external pull-up resister.   Is it correct?

Also, How about non-connection status?  If TUSB322I has not detected CC1/CC2, TUSB322I outputs open and same behavior as CC2 detection.  Is it correct?

 

  • EN_N pin treatment

Is it OK to connect GND with EN_N pin directly?   Although EN_N pin is directly connected with
GND on typical application circuit of the datasheet, I want to re-confirm it.  Please let us know.

 

  • INT_N/OUT3, ID pin pull-up resister.

According to the datasheet, pull-up resister of INT_N/OUT3 pin and ID pin recommends 200kohm.  However, due to external CPU requirement, he wants to reduce 10kohm pull-up resister.  If you know any issues to use 10kohm resister, please advise us.

Thanks and best regards,
M.HATTORI.

  • +1
    TI__Guru*** 146615 points

    *DIR:  DIR is used to control USB Mux, when nothing connected or position 2 (CC2) connected it's H.

               it goes low when CC1 is connected.

    *EN_N yes it can be ground directly.

    IN_N/Out3, ID: 10 k may still work, but very marginal, suggest 100k or up

    regards

    brian

  • 0 in reply to Brian Zhou
    TI__Genius 11095 points

    Hi, Brian-san,

    According to the datasheet, VOL is MAX 0.4V when IOL=-1.6mA on INT_N/OUT3 pin and ID pin.  So internal pull-down resistor is 0.4V/1,6mA=250ohm.   If these pins are used on 3.3V through 10kohm pull-up resistor, Vout is 0.089V and these voltage is acceptable for his CPU (connected with INT_N/OUT3 pin or ID pin),  So he wants to use 10kohm pull-up resistor.  Do you have any concerns?  Also, could you please let us know the reason why TI recommends 200kohm(typ) pull-up resistor?   Please advise us.

    Thanks and best regards,
    M.HATTORI.

  • 0 in reply to Motoyasu Hattori
    TI__Guru*** 146615 points

    HATTORI:

             design said internal pulldown is round 5k, not 250ohm. so 10k pull up is marginal. that's why we suggest 100k up.

    Thanks

    Brian

  • 0 in reply to Brian Zhou
    TI__Guru**** 177836 points

    Hattori-san

    >design said internal pulldown is round 5k, not 250ohm. so 10k pull up is marginal. that's why we suggest 100k up.

     

    As the background, he considers PTN5150A + NXP’s Processor.  PTN5150A and Processor recommends 10kohm external pull-up resistor, but TUSB322I recommends 200kohm.  So, as of now, it is easier to connect PTN5150A and Processor.

    We have to propose the minimum value of external resistor, 100k ohm is too large for processor.   (How about 47kohm?)

    *1.

    According to the datasheet of TUSB322I, VOL is 0.4V (MAX).  Also you said internal pull-down resistor is round 5kohm.  IoL=0.4V/5kohm=80mA,  Ext_Reg = (3.3-0.4V)/80mA=36.25kohm.   So does TI suggest >=40kohm external resistor?   Please advise us.

    The ID pin is an open drain output. The voltage that the pin is pulled up to does not matter as much as the current following through the open drain output of TUSB322I. If the current following through the input exceeds Iol then the "low" voltage may not be seen on the node. In short, the pull up voltage and pull up resistance can be varied however care needs to be taken to ensure that a "low" voltage is actually achieved. TI does recommend using pulling these pin up to 5V or VDD. So with 5V, the calculation will be (5-0.4)/80mA = 57.5k.

    *2.

    Also, he worries about 5kohm pull-down variation on all temperature/devices.  Does TI submit any variation data of pull-down resistor?   Please advise us

    We do not have this data available. Recommendation in the datasheet is 100k and up to guarantee a "low" voltage is seen on the ID pin.

    Thanks

    David 

  • 0 in reply to David (ASIC) Liu
    TI__Genius 11095 points

    Hi, David-san,

    Thank you for your support.  I have one question again.

    In general, "Open Drain" pin is independent of pull-up voltage, and most high-end processors supports only 3.3V I/O.  So users wants to use "INT_N/OUT3 pin and ID pin" with 3.3V pull-up.  Is it difficult to use 3.3V pull-up on these two pins?   Please advise us.

    Thanks and best regards,
    M.HATTORI.

  • +1 in reply to Motoyasu Hattori
    TI__Guru**** 177836 points

    Hattori-san

    When VDD is off, TUSB322I non-failsafe pins (VBUS_DET, ADDR, PORT, ID, OUT[3:1] pins) could back-drive the device if not handled properly. When necessary to pull these pins up, it is recommended to pullup PORT, ADDR, INT_N/OUT3, and ID to the device VDD supply.

    So if you want to use 3.3V supply, you have to make sure 3.3V is off first before VDD is off so back-driving will happen.

    Thanks

    David 

  • 0 in reply to David (ASIC) Liu
    TI__Genius 11095 points

    David-san,

    Thanks a lot.

    Best regards,
    M.HATTORI.