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TUSB4041I-Q1: USB hub not detected in some boards

Ebin MJ
Prodigy 20 points
Part Number: TUSB4041I-Q1

Hi,

I am using TUSB4041 as USB hub in my design. I need total 6 USB ports, so two USB hubs are used. USB upstream is connected to a processor and down streams are connected to 5 devices and a connector. My problem is USB hubs detected in some boards but in others it is not detecting. I have checked the 24MHz clock, 3.3V and 1.1V power rails, all are good. And also checked the power on sequence, 1.1V will come before 3.3V. I have checked with PC also by isolating the processor and directly connected to the PC, but not detecting. Can anyone suggest some solutions ? I have attached the schematics here.

SCHEMATIC1 - USB HUB.pdf

  • 0
    TI__Guru 60870 points

    Hi,

    Have you tried increasing reset timing, by increasing the 1 uF on GRSTz?  How slow is the supply voltage ramp time on your boards?

    One possible issue is the USB_VBUS is a detection input and should not be high until an active host is connected to the hub.  If this is going high before the host is out of reset, the host and the hub could get out of sync.

    Can you probe the DP / DM lines between the host and the hub and share what is happening when the hub is not detected?

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 20 points

    Hi JMMN,

    Thanks for your suggestions.

    We have ensured the hub power and USB_VBus is enabled only after the host device is switched ON. This we tried from a Linux based host and also from a windows based host. Still the hubs are not detected by the hosts.Also we checked the voltage on the DP+ and this is always low (on DP- also).We are unable to probe the USB differential signal transitions currently (lack of access to equipment due to lockdown). Is there anything else we can try at this time?

    Regards

    Ebin

  • 0 in reply to Ebin MJ
    TI__Guru 60870 points

    Can you confirm the voltage on the USB_VBUS line is around 500 mV?  Also, what is the voltage on the USB_R1 pin?  Is the clock running or does it stop?  Is there adequate solder paste connecting the thermal pad of the hub?

    Regards,

    JMMN

  • 0
    Prodigy 20 points

    Hi JMMN,

    Due to covid lockdown, I cant access the system as I am in another location. I will update you once I access the system.

  • 0 in reply to Ebin MJ
    TI__Guru 60870 points

    Ok, no problem.  Update the thread when you are able.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 20 points

    Dear JMMN,

    I have replaced the USB hub IC. Now it is working. While removing the IC, we saw a dry solder. May be this is the issue. Any way now it is working. Thanks for your valuable feedbacks and suggestions.

    Regards

    Ebin