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TUSB8041: TUSB8041 VBUS QUESTION

Part Number: TUSB8041
Other Parts Discussed in Thread: , TPS2066

HELLO, I am going to use TUSB8041 for connecting four usb 3.0 devices.

I want to give USB VBUS from the PMIC in my board.

I want to control USB signals(SSTX, SSRX, DP, DM) only with TUSB8041A like below simple block diagram.

In this case,

.

how should I set PWRCTL1~4 pin,  Ganged, PWRCTL_POL., FullPWRMGMT pins?

Because I am using external USB VBUS Power(from my pmic), then these PWRCTL Pins are floating, or to gnd?

Or Is these also should be used as control USB Signals?(SSTX, SSRX, DP, DM)

.

Thanks.

  • Hello Shen,

    If you are not using the hub to control downstream port power switches, the setting should be:

    FULLPWRMGMTz = 1

    GANGED = no connect

    PWRCTL_POL = no connect

    PWRCTL1-4 = no connect, do not install pullups since it will enable battery chargring support.

    Please note that USB compliance requires that a hub report overcurrent events on its downstream ports via the OVERCURz inputs, but it is not required for a closed system.

    Also, note that USB_VBUS to the hub should only be high when an active host is connected to the upstream port.  If USB_VBUS is high before the host is ready to connect, the host and hub could get out of sync leading the hub to enter compliance mode.

    Regards,

    JMMN

  • Thanks for detail reply. JMMN. 

    I understood.

    Then, If I use two TPS2066 with TUSB8041 to control USB Power and overcurz. then How can I control this TUSB8041's PWRCTL?

    I want to control Enable USB devices by AP or MCU with gpios.

    But In the datasheet there just says TUSB8041's PWRCTL1~4 will be used for control of the downstream power switch.

    .

    If I connect TUSB8041's PWRCTL to TPS2066 to control Power Enable, then how can I on/off this PWRCTL Pin? 

    .

    I searched for other usb hub of TI. AND TUSB2046 has similar block diagram.

    And this also shows no external AP or MCU to control Enable.

    I will look forward to your reply again. Thanks.

  • Hello Shen,

    The downstream port power controls of the hub are handled as part of the USB protocol.  The USB host controller will send port power on/off commands to the hub as outlined in the USB 2.0 / 3.0 specifications.  

    Please accept my friend request and I will send you some notes on the USB specs.

    Regards,

    JMMN

  • Thanks for your kindness and very quick reply.

    I accepted friend. I will read your notes. Maybe this is my last question for this.  

    .

    Then If I use TPS2066 witth TUSB8041, then is this mean I can't control On/Off for USB downstream device with my AP or MCU's GPIO right?

    Because USB Host controller will send port power on/off commands automatically refer to USB 2.0 3.0 Spec like plug and play. ?

    .

    But I don't understand this.

    To connect USB devices, I thought VBUS must be connected firstly then check D+/D- 's voltage to detect the device as below.

    How will TUSB8041 detect and know if any downstream USB Device and enable pwrctl switch to give VBUS to USB Device?

     

    .

    Anyway, If I will use two TPS2066 with TUSB8041 for my system to control each USB Port and Overcurrent detection. 

    And could you check below pin configuration?

    1. PWRCTL Pins

    : Connect to TPS2066 Enable pin. (TPS2066 EN is active high)

    : I am not going to us Battery charge support so Pull-Up R is not needed. Right? 

    .

    2. FULLPWRMGMT Pin

    : Pull down to gnd to Power switch control. Right?

    .

    3.PWRCTL_POL 

    : ??NC? I don't get what exactly this pin means.

    4. Ganged 

    : : Pull down to gnd for individual power control. Right?

    What does it mean power control gangs when this is high?

    Thanks.

  • Hi Shen,

    Typically a USB host will enable port power on all the downstream ports of a hub after enumerating the hub, so then any connected downstream devices can be detected.

    1. PWRCTL Pins

    : Connect to TPS2066 Enable pin. (TPS2066 EN is active high)

    : I am not going to us Battery charge support so Pull-Up R is not needed. Right? 

    .[JMMN] Yes, this is correct

    2. FULLPWRMGMT Pin

    : Pull down to gnd to Power switch control. Right?

    ..[JMMN] Yes, this is correct

    3.PWRCTL_POL 

    : ??NC? I don't get what exactly this pin means.

    .[JMMN] This pin can be used to change the polarity of the PWRCTL outputs for active low power switches.

    4. Ganged 

    : : Pull down to gnd for individual power control. Right?

    What does it mean power control gangs when this is high?

    .[JMMN] GANGED means that two or more ports are powered off a single power switch, it is not common.

    Regards,

    JMMN

  • Thanks!!!! Your comments would be very helpful to me.