• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 3 answers
  • Subscribers 34 subscribers
  • Views 786 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TUSB4041I: No response from USB after powering up the device

Patrick Chaopricha
Prodigy 30 points
Part Number: TUSB4041I
Other Parts Discussed in Thread: TUSB4041PAPEVM, TPS74801

Hello,

    I made a demo board for an 8-port HUB using 3 TUSB4041I.  I used the design from the evaluation board TUSB4041PAPEVM but stripped out the EE-prom portion.  I kept all the power control ICs and I followed the guidelines from the chip datasheet.   After assembling the board, all the ports provide power when plugging a USB device to the port.  However, there's no USB data connectivity.  The main IC also doesn't show up in the device manager under Windows 7.  The eval board shows up as a USB 2.0 MTT Hub.   This suggests to me that the IC isn't interfacing to the computer via USB correctly.

   I attached the schematic.  Basically I use Master Hub to controller the 2 daughter hubs.   I only use 2 USB lines from the Master Hub.   On my board, all the USB lines are differential pairs when I route them.  I tried to imitate the layout design on the eval board as much as I could.  I'm not certain whether I'm missing something obvious to get this to work.

Thanks,

PatrickUSB_Hub_Demo.pdf

  • 0
    TI__Guru 64326 points
    Patrick,
    This sound like TUSB4041I Master is not enumerating correctly and thus the daughter TUSB4041I are not enumerating correctly. I would check your solder connection on the ground pad. Please check Vbus or USB_Vbus pin to check for voltage sag due to power consumption. Also please check the power up sequence and make sure it is inline with the datasheet of each hub and that the clock of each hub is starting appropriately.
  • 0 in reply to Malik Barton57
    Prodigy 30 points

    Hi Malik,

       Thank you for the response.  I decided to remove the 2 daughter TUSB4041 from the board so that it's just the Master TUSB4041I on the board.  I checked the USB_Vbus pin and I have 558 mVolts steady there from the voltage divider 90.9k and 10k as recommended by the datasheet and VBUS is a steady 5.21V.  I'm going to try to check the power up sequence again.  Right now 1.1V comes on about 3 ms after the 3.3V due to the capacitor on the soft start function for the TPS74801 IC I have for 1.1V.  Is that actually problematic because right now my GRSTz pin is only connected to a 1 uF capacitor.  According to note 2 in the data sheet:

    The VDD33 and VDD have no power-on relationship unless GRSTz is only connected to a capacitor to GND. Then VDD must be stable minimum of 10 μs before the VDD33.

    Does this mean that I need to get VDD to be stable at 10 uS before the VDD33??  I just realized that I didn't follow the same power outline recommendation of having VDD_board and then ferrite and then a bunch of decoupling caps then VDD.  I suppose that's how I can delay the start up time of VDD33 to be 10 us after VDD11.

    I'm somewhat confused by the GRSTz pin.  How does it ever pull high if I just have a by pass cap on the pin?   Do I need to hook this up to an MCU to assert the pin high manually?

    Thanks,

    Patrick

  • 0 in reply to Patrick Chaopricha
    TI__Guru 64326 points
    Patrick,

    Yes, if a capacitor to GND is used on GRZT then VDD needs to be stable at 10 uS before the VDD33. GRSTz has a internal pull up resistor which charges the capacitor. It sounds like you need a active reset that can come from a MCU if you cannot change the power up sequence.
  • 0 in reply to Malik Barton57
    Prodigy 30 points

    Hi Malik,

       I forgot that my VUSB_BUS line that turns on the power to TUSB4041I doesn't get active until I plug the USB connector in.  This means that both 3.3V and 1.1V supplies are already on well before the VUSB bus is on to get the GRZT to charge the capacitor.  I manage to get the TUSB4041I to show up now in my Device Manager list the same way the eval board does.

       This works after I reheated the back side of the IC and put some more solder through the via to make sure that the back side ground pad is connected.  After I did that it worked!!!   Thank you for suggesting checking the Ground.

       Now I'm going to try to solder the other 2 TUSB4041I chips back on and see whether I can now get the USB connectivity to come through.

    Thanks,

    Patrick