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TPS25830-Q1: LS_GD required for Type-C port?

Shinji Tsuji
Genius 12338 points
Part Number: TPS25830-Q1

Hi team,

I have a question about the use case of the external NMOS FET on output.

Is that a requirement for USB Type-C port? or it is just a nice to have function?

If it is not necessary, I plan to remove it from my schematic, but I would like to make sure it can pass USB

certification without this FET.

regards,

  • 0
    TI__Expert 8420 points

    Hi Tsuji-san,

    It don't necessary to use the external FET.

  • 0 in reply to Michael Tan
    TI__Genius 12338 points

    Hi Michael,

    In the datasheet, VBUS short to VBAT is described as below. In my case, VBUS short to VBAT protection is necessary.

    In this case, do I need external back to back FET on VBUS?

    What is the reason why you suggest the external FET in real application?

    "In real application, if VBUS short to VBAT function is needed, 20-V back-to-back NFET is suggested in circuit
    design."

    regards,

  • 0 in reply to Shinji Tsuji
    TI__Expert 8420 points

    Hi Tsuji-san,

    The external FET function summary as below: 

    1. USB client mode ( In Client mode the VBUS should not have output voltage , that mean need external FET to shut down the VBUS.)

    2. Use for block the Vcsn and VBUS when the Vcsn have addition loading

    3. 7V OVP protection , when the BUS pin above 7V , the LS_GD will turn off external FET

    It don't need add this external FET for the VBUS short to battery .

  • 0 in reply to Michael Tan
    TI__Genius 12338 points

    Hi Michael,

    1. Does USB client mode mean CarPlay type of host swap use case? In that case, if I use this for CarPlay, should I need to use external FET?

    3. When VBUS short to VBAT which is higher than 7V, then BUS pin will pull output Low for discharge function?

    regards,

  • 0 in reply to Shinji Tsuji
    TI__Expert 8420 points

    Hello Tsuji-san,

    Below is the comment :

    1. Does USB client mode mean CarPlay type of host swap use case? In that case, if I use this for CarPlay, should I need to use external FET?

    --> NO, Carplay general use the CDP mode. It needn't to add the FET. The client mode use for the Head Unit software update (host and slave swap)  and power is come from PC or Note book , it need FET to block the energy which come from TPS25830 device.

    3. When VBUS short to VBAT which is higher than 7V, then BUS pin will pull output Low for discharge function?

    -->NO, the VBUS higher than 7V, the external FET will turn off and the discharge function be not active.