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TUSB2046BVF Crystal problem

Duarte Carona1
Prodigy 70 points
Other Parts Discussed in Thread: TUSB2046B

Hi,


I'm using TUSB2046BVF on our design and i'm experiencing a problem with my crystal (Datasheet) where  sometimes (not always) the crystal is not oscillating correctly and the device is not recognized by Windows.


I'm using the suggested circuit on hub datasheet where C1 and C2 has 27pF and series resistor 1.5K.

Also the RESET circuit of hub has a RC circuit with 27R and 1uF to ensure the power-up time.


When the crystal is not working i get about 3.3V in one side and approx 0V on the other. When the circuit is working fine i have about 1.5V on both sides.


Does anyone has an idea about why is this happening?


Thank you.


Regards,

Duarte Carona

  • 0
    TI__Mastermind 18655 points

    Hello Duarte,

    This looks like the TUSB2046B is going into suspend mode. Can you post the schematics?
    Please, change the reset resistor to 1kOhm.

    Regards.

  • 0 in reply to Joel Jimenez0
    Prodigy 70 points

    Hi Joel,

    Thank you for your reply.


    Actually i've already changed it to 15kOhm and it is working now. I've seen on another post a suggestion to use a 15K resistor on RC circuit and it is working fine now.

    Thanks for the tip.


    Regards

  • 0 in reply to Duarte Carona1
    Prodigy 70 points

    Hi Joel again,


    Suddenly my HUB stopped working and now is always in suspend mode, i've changed the Resistor on the RC circuit of reset to 1Kohm as you suggested before but it still is on Suspend.

    Below you can find my schematic and the resistor i'm changing is R22. Can you please tell me if i'm doing something wrong?


    Thank you.

  • 0 in reply to Duarte Carona1
    TI__Mastermind 18655 points

    Hello Duarte,

    I need to verify if the required passive components are populated on the DP and DM lines. Please send the schematic to joel.jimenez@ti.com

    Regards.

  • 0 in reply to Joel Jimenez0
    TI__Mastermind 18655 points

    Hello Duarte,

    I reviewed your schematic and just have a comment:
    Remove the pull-up resistor from DM0 (R16).

    For the upstream port, according to the USB specification, you must connect a pull-up resistor of 1.5 kΩ on D+ for full and low speed devices OR on D–  only for low-speed devices.

    Regards.

  • 0 in reply to Joel Jimenez0
    Prodigy 70 points

    Hi Joel,


    R16 is not mounted, i have only the pads available. R20 is mounted with a value of 1.5kohm.


    However, the HUB is not recognized by windows and as soon i power it, SUSPEND goes immediately high.


    Regards.

  • 0 in reply to Duarte Carona1
    Prodigy 70 points

    Hi Again,


    I forgot to mention that i removed Q2 and R20 is connected directly to 3.3V.


    Regards

  • 0 in reply to Duarte Carona1
    Prodigy 70 points

    Hi Joel,


    I've connected the board to a linux OS and i get the following log messages:

    [ 1247.503119] usb usb1: usb wakeup-resume
    [ 1247.503217] usb usb1: usb auto-resume
    [ 1247.503266] hub 1-0:1.0: hub_resume
    [ 1247.503362] hub 1-0:1.0: port 1: status 0101 change 0001
    [ 1247.605887] hub 1-0:1.0: state 7 ports 1 chg 0002 evt 0000
    [ 1247.605997] hub 1-0:1.0: port 1, status 0101, change 0000, 12 Mb/s
    [ 1247.711251] usb 1-1: new full-speed USB device number 10 using musb-hdrc
    [ 1247.825349] usb 1-1: device descriptor read/64, error -71
    [ 1248.039808] usb 1-1: device descriptor read/64, error -71
    [ 1248.254222] usb 1-1: new full-speed USB device number 11 using musb-hdrc
    [ 1248.367484] usb 1-1: device descriptor read/64, error -71
    [ 1248.582324] usb 1-1: device descriptor read/64, error -71
    [ 1248.797265] usb 1-1: new full-speed USB device number 12 using musb-hdrc
    [ 1249.211277] usb 1-1: device not accepting address 12, error -71
    [ 1249.322556] usb 1-1: new full-speed USB device number 13 using musb-hdrc
    [ 1249.736626] usb 1-1: device not accepting address 13, error -71
    [ 1249.744164] hub 1-0:1.0: unable to enumerate USB device on port 1
    [ 1249.751551] hub 1-0:1.0: state 7 ports 1 chg 0000 evt 0002
    [ 1249.751628] hub 1-0:1.0: port 1 enable change, status 00000101
    [ 1249.751792] hub 1-0:1.0: hub_suspend
    [ 1249.751863] usb usb1: bus auto-suspend, wakeup 1

    It seems that the hub have some enumeration problems.


    Regards.

  • 0 in reply to Duarte Carona1
    TI__Mastermind 18655 points

    Hello Duarte,

    Verify whether the DP0 and DM0 lines are connected correctly on the board.

    Could you provide some trace captures using a USB protocol analyzer between the host and the TUSB2046B    ?

    Could you take some scope captures of the RESET, VCC and XTAL lines in power up?

    Regards.

  • 0 in reply to Joel Jimenez0
    Prodigy 70 points

    Hi Joel,


    Unfortunately i do not have a USB network analyzer. The DP0 and DM0 are routed as differential pair with the same length. I'll try to get some captures with an Oscilloscope.

    Regards.