• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 3 answers
  • Subscribers 32 subscribers
  • Views 798 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPD1S414: TPD1S414 EN status

Ann_Lien
Genius 10640 points
Part Number: TPD1S414
Other Parts Discussed in Thread: TPD4S014

Hi Expert,

My customer has a question on TPD1S414 EN status. They have an AIO PC application and want to use TPD1S414 at USB TypeC port.

They want to know internal MOSFET status when EN is floating and VBUS_CON 5V exist.

The reason that they have this question is MB will be no power when adapter is absent. In the other words, EN will be no pull up power rail in MB and it would be floating. They want to make sure VBUS power would not go to MB(block by internal MOSFET)

Could you kindly help to answer it? Thanks a lot!!

Best regards,

Ann Lien

  • 0
    TI__Mastermind 25870 points

    Ann,

    In order to have the TPD4S014 do what they want to to, they will need to apply a circuit similar to this one between the VBUS_SYS output pin and the /EN Pin.

    This circuit, when sized correctly, will pull the /EN pin high then low long enough to meet the internal reset timing.  This will make the TPD1S414 do what your customer wants.

  • 0 in reply to Chuck Branch
    TI__Genius 10640 points

    Hi Chuck,

    Thanks for reply!!

    Since MB will have no power on VBUS_SYS, so that /EN will have no power rail to pull it to high. In this scenario, our VBUS_CON may connect a 20V. Will /EN be determined low to let current flow from VBUS_CON to VBUS_SYS? That's what customer want to know.

    Best regards,

    Ann Lien

  • 0 in reply to Ann_Lien
    TI__Mastermind 25870 points
    Ann,

    In this case, the customer will not use the circuit I showed, and must add a weak pull-down resistor on /EN to ensure that the switch will be enabled without power being applied internally.

    Regards,
    Chuck
  • 0 in reply to Chuck Branch
    TI__Genius 10640 points
    Hi Chuck,

    Thanks for reply!

    For our purpose, we don't want VBUS_CON power go through VBUS_VSYS(we want to block by internal FET).
    So if /EN is floating, would the internal MOSFET turn on possibly to let TYPEC port power go through MB?
    Thanks!

    Best regards,
    Ann Lien
  • 0 in reply to Ann_Lien
    TI__Mastermind 25870 points
    Ann,

    If the /EN pin is truely floating, then the gate of the power device is not determined. The system is designed so that if the /EN pin is grounded, then the switch will be closed and if it is pulled to a voltage greater than 1.2V, then the switch will be disabled. Does your customer have a power supply that will be active in the case that you want to block VBUS_SYS? If they do, then the can put a pull up resistor to that supply from the /EN pin to ensure that the fet is disabled.

    Regards,
    Chuck
  • 0 in reply to Chuck Branch
    TI__Genius 10640 points
    Hi Chuck,

    Thanks for reply!

    Since MB will have no power on VBUS_SYS, so that /EN will have no power rail to pull it to high. So we cannot promise if this part would b enabled when /EN is floating, right? Thanks!

    Best regards,
    Ann Lien
  • 0 in reply to Ann_Lien
    TI__Mastermind 25870 points
    Ann,

    /EN should be held low to enable the switch and pulled high to disable to switch. There is some internal circuitry to the chip that will not be properly reset unless EN transitions from high to low.

    We cannot guarantee functionality of the part if /EN is floating.
  • 0 in reply to Chuck Branch
    TI__Genius 10640 points
    Hi Chuck,

    Got it, thanks for confirmation!

    Best regards,
    Ann Lien