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TUSB2046B: Help to review TUSB2046B sch

Part Number: TUSB2046B

Hello E2E,

Please help to review TUSB2046B sch as attachment.

The one port of TUSB2046B will connect to a certain module while another one will connect to USB connectot.

Beside to the sch review, there are three questions listed in below.

Q1: What is the main function of GANGED pin as pin 6?

Q2: For pin8, if customer wants to use self-powered mode, could customer pull pin8 to GND or need to through a series resistor 2.2k to GND?

Q3: regrading to VBUS, since DM0, DP0 and DM1, DP1 connect to a chip, so it doesn't need external VBUS(5V). Please advise.

~Jason 

  • Hi Jason,

    Please be aware that the  TUSB2046B is a USB full speed hub, not high speed hub.  The application requires a 1.5K pullup on the upstream DP line and 15K pulldowns on the downstream ports.

    A1.  Ganged indicates if the hub switches port power individually on each port or to all downstream ports as a group.  For this application, downstream port power switches are not implemented so it does not matter.

    A2.  BUSPWR can be tied low directly or through a resistor.

    A3. That is fine, the PWRON outputs can be left unconnected.

    Regards,

    JMMN

  • Hi JMMN,

    Please help to check update schematic, thanks.TUSB2046 schematic_1029.pdf

    There are some questions as follows, please also advise it, thanks.

    1. Does OVRCUR pull high to 3.3V are fine?

    2. any power sequence problem for this hub? 

    3. downstream DM/P1 port doesn't have VBUS, is that ok? 

    Sincerely,

    Tim

  • Hi Tim,

    Updated schematic looks good.

    1. Pullups on OVRCUR are good.

    2. Power sequencing is not a concern here.  In general in embedded applications you want to be sure not to hold the hub in reset so long it misses initial signaling from the host, but with a passive reset circuit that is not an issue.

    3. As long as everything is powered the hubs are not impacted by VBUS.

    Regards,

    JMMN