• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 33 subscribers
  • Views 671 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.

TUSB8041: TUSB8041 crystal oscillations dying out

Suhas Raja Chandragupta55
Intellectual 1690 points
Part Number: TUSB8041

Hi Team,

Greetings!

TUSB8041 device is being used at my customer in a new design. We are facing a challenge where the 24MHz crystal oscillations are dying out. We are able to observe the oscillations on initial power-ON (on oscilloscope) before it dies out. The below crystal is being used in the application. 

http://www.txccorp.com/download/products/quartz_crystals/2015TXC_8Z_16.pdf

I suppose the ESR of the crystal maybe loading the device.

TUSB8041 datasheet recommends using 1MOhm resistance across the crystal. Is it possible to tune the resistance to prevent loading on the device and to obtain sustained oscillations? Kindly request your suggestions. Thanks in advance!

Best Regards,

Suhas R C

  • 0
    TI__Guru 60870 points
    Hi Suhas,

    What is the functional issue here? Is there a valid upstream connection to the hub? If not, the hub will enter low power mode (suspend) and turn off the clock circuit to lower power consumption. Also, many USB drivers will enumerate a hub, then put it back in low power mode if there are no downstream devices attached. Any time the hub is in low power mode, the crystal will not oscillate.

    Regards,
    JMMN
  • 0 in reply to JMMN
    TI__Intellectual 1690 points

    Hi JMMN,

    Yes, there is a valid upstream connection to the hub. The issue is that we are unable to communicate (or transfer data) through the USB hub as the crystal is not oscillating.

    Is the ESR of the crystal alone causing the issue here?

    Best Regards,

    Suhas R C

  • 0 in reply to Suhas Raja Chandragupta55
    TI__Guru 60870 points

    Suhas,

    The ESR of the crystal is not ideal, but if it starts oscillating it is likely not the root cause of the issue.  The TUSB8041 turns off the crystal in low power mode, can you confirm if DP is pulled high by the TUSB8041 when the crystal stops oscillating?

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Intellectual 1690 points

    Hi JMMN,

    Thank you for your suggestion. The device was in low power mode and was coming back to normal operation during data transfer.

    Best Regards,

    Suhas R C