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TUSB2046B: TUSB2046 Hub Design Review

Jegatheeswari Seenivasan
Prodigy 50 points
Part Number: TUSB2046B

Hi,

We are using TUSB2046 Hub in our design for managing 3 ports and we used USB MuX Switch also for this purpose. We gonna use OTG USB from our target device processor.

Please anybody review the circuits to confirm this design flow will workout.sch_501-1-00513_b0_03_20180212-3-12-12.pdf

  • 0
    TI__Expert 7395 points
    Hello,

    I have some observations on your TUSB2046B implementation:

    1- All USB DP, DM signal pairs require series resistors of approximately 27 ohms to ensure proper termination. An optional filter capacitor of about 22 pF is recommended for EMI suppression. This capacitor, if used, must be placed between the hub terminal and the series resistor, as per section 7.1.6 of the USB specification.
    2- You also need to add a 1.5K PU resistor to DP0. (Refer to figure 11 on the datasheet)
    3- If using PU/PD resistor on the configuration terminals, please use resistors with lower values (4.7K is recommended). For example R999 at BUSPWR, R995 at TSTPLL, R994 at TEST_MODE and R1001 at EXTMEM.
    4- Add a 1.5K resistor to the XTAL2 terminal to trim the oscillator's gain as shown at figure 6 on the datasheet
    5- Make sure your implementation of the USB_HUB_RST# follows the guidelines defined by the datasheet at the RESET pin function description.

    Regards,
    Jorge
  • 0 in reply to Jorge Llamas (SWAT)
    Prodigy 50 points

    Hi Jorge Llamas,

    Thanks for the review comments. Its helpful. Also I need one more clarification in the below quoted text by you,

    "- All USB DP, DM signal pairs require series resistors of approximately 27 ohms to ensure proper termination. An optional filter capacitor of about 22 pF is recommended for EMI suppression. " - I belive this is applicable between USB Connector and Hub. But Interms of USB communication between USB Host (imx6 processor) and USB HUB(TUSB2046), is that series termination resistor and emi suppression capacitor really needed ??