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ISOUSB111DWXEVM: Is it possible to isolate HUB

Guerineau Damien
Prodigy 10 points
Part Number: ISOUSB111DWXEVM
Other Parts Discussed in Thread: ISOUSB111

Tool/software:

Hi Team,

We developed customized board with four isolated usb downstream ports (for low and full speed device). Our solution is PHY USB (USB3315 by Microchip) connected to USB isolator (ISOUSB111) and connected to HUB USB (USB2534 by Microchip)

However our solution doesn't work with isolator (connecting mouse device (low speed device) to the HUB it's resetted, connecting storage device (full speed device), it works).

Moreover, when PHY USB is connected to HUB without isolator it works with mouse or storage device.

Is it possible to connect ISOUSB111 between Host (PHY USB) and HUB USB to work in low and full speed ? Any configurations that need to be checked ?

Regards

Damien

  • 0
    TI__Mastermind 30635 points

    Hello Guerineau, 

    Thank you for reaching out. The ISOUSB111 should be able to connect Host USB and HUB USB in low and full speed. Please allow us another day to review the other devices and get back to you. 

  • 0
    TI__Expert 8490 points

    Hi Damien,

    Thanks for reaching out.

    Yes, the ISOUSB111 can be used perfectly between Host and HUB/Peripheral.

    A block diagram showing all downstream hubs connections along with host and Peripheral Device will be helpful in understanding the system for us to debug. Can you please provide that?

    One Information that I would like to bring upfront is that ISOUSB111 uses 2 hub budgets in the USB2.0 seven tier connection. Knowing this information - Please make sure that the total tier is not exceeding 7 including host and peripheral.

    Regards
    Varun

  • 0
    Prodigy 10 points

    Hi Team,

    Thank you for your replies.

    The following block diagram describes our system :

    Note : PHY USB is also used to enable isolated 5V and 3V3

    When devices in full speed, the links is correct. When devices in low speed, the link is incorrect and HUB is resetted.

    Regards

    Damien

  • 0 in reply to Guerineau Damien
    TI__Expert 8490 points

    Hi Damien,

    Thanks for the inputs. It really helps in understanding the system better:

    Looking at the block diagram on a top level I cannot see any reason why ISOUSB111 should not work here, and based on one statement from your initial statement - it actually does work (for FS storage device)

    So, it is definitely not the ISOUSB111 basic functionality which is compromised here. It looks more of a system level issue

    Please do check the power budgeting on HUB side which powers ISOUSB111 right side and HUB+Peripheral Device (Mouse/Storage Device) - it may be possible that mouse is taking more current that storage device and that somehow it is causing voltage to drop and that is how the HUB is getting reset by POR:

    Guerineau Damien said:
    connecting mouse device (low speed device) to the HUB it's resetted

    ISOUSB111 cannot reset the HUB with D+/D- - Hence this issue is independent of ISOUSB device.

    I don't have any other inputs to provide beyond this.

    Regards
    Varun

  • 0 in reply to Varun Kumar
    Prodigy 10 points

    Hi Varum,

    Thank you for your reply.

    Power management on HUB side has been verified and appears to be correct

    At the same time, I replace ISOUSB111 with an equivalent component (ADUM4160 + serial resistor on USB line) and it works as expected.

    I don't see much difference between these two components, except that the speed is fixed by HW for ADUM4160.

    Do you have any idea why this works with another component ?

    Regards

    Damien

  • 0 in reply to Guerineau Damien
    TI__Expert 8490 points

    Hi Damien,

    Thanks for the details and inputs on ADUM4160. 

    Can you share the schematic and PCB layout for ISOSUSB111 for us to review?

    Question - While using ISOUSB11, what is the value of series resistors on the USB line? 

    Also, please share a zoomed in picture of the device showing the lot number/device name on the top of the device

    Regards
    Varun

  • 0 in reply to Varun Kumar
    Prodigy 10 points

    Hi Varum,

    Thanks for your reply.

    It's not possible to me to share you schematic and layout. However, USB signals are clean and power supply is stable.

    We don't use series resistors on the USB line with ISOUSB (ISOUSB already have this resistor between 28Ω and 44Ω ?). For ADUM4160 we add 24Ω resistor on both side.

    On the top of the device:
    ISOU111
    27T G4
    APE4
    Regards
    Damien
  • 0 in reply to Guerineau Damien
    TI__Expert 8490 points

    Hi Damien,

    Thanks for the update on series resistors. I understand the confidentiality behind not sharing the schematic and layout so can you review your schematic connections and layout keeping ISOUSB111 EVM as a reference? And mention the differences, if any.

    We'll need one actual picture of the device topside to extract the information we need to investigate the origin of this device. Can you please provide that?

    Regards
    Varun

  • 0 in reply to Varun Kumar
    Prodigy 10 points

    Hi Varum,

    We checked ISOUSB111 EVM schematic and found no difference in the connections. The layout is obviously different, but we don't see any differences that could explain why it's not working.

    The following picture shows our device :

    Regards
    Damien
  • 0 in reply to Guerineau Damien
    TI__Expert 8490 points

    Hi Damien,

    Thanks for confirming on the Schematic being same ISOUSB111 EVM and yes layout change does not affect that much but the supply decoupling capacitor positioning can be a factor, but I believe you have taken care of that as per the layout guidelines in datasheet.

    On the Device you're using, when did you order these devices? - Let's discuss about this privately.

    Regards
    Varun