• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 32 subscribers
  • Views 3986 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.

TUSB2046 reset condition

Bruce Doan
Prodigy 80 points
Other Parts Discussed in Thread: TUSB2046B

What are the requirements to assure that the TUSB2046 starts (xtal clock runs)?

I start my uP driving the Reset pin high on power up and then hold it low for 1.5mS and then high again.

I see that sometimes, the xtal starts and then stops.


What other conditions will cause the clock to stop?

  • 0
    TI__Mastermind 18655 points
    Hello Bruce,
    The clock will be stopped at logic low whenever the TUSB2046 goes into SUSPEND mode, this will occur after 3 ms of downstream ports inactivity or enumeration errors.
    Could you provide your schematics? We can review them and provide you feedback.
    Best Regards,
  • 0 in reply to Joel Jimenez0
    Prodigy 80 points

    Does the TUSB actively pull down on the D+ and D- of each downstream port when it goes inactive?

    If so, how can a device trying to connect pull the line high to wake the hub and request enumeration?


    The reset input is controlled by the micro.

    D+ and D- for the micro have no pull downs (15k)

  • 0 in reply to Bruce Doan
    Prodigy 80 points

    If I hold the TUSB2046 reset low, the oscillator runs.

    When I release the reset, the device goes into suspend Windows says that it does not recognize the USB device.

    How do I keep the TUSB2046 from suspending (or shutting down the oscillator) long enough for it to enumerate with the host ?
    What makes this more confusing is that 2 other identical PC board enumerate just fine.


    This issue is critical for me to be able to support production testing of our product.

    Please contact me and arrange a telephone conference to resolve this issue.

  • 0 in reply to Bruce Doan
    TI__Mastermind 18655 points

    Connect the EXTMEM\ terminal to high and EEDATA pin to low.
    It appears that it is related to the power-up sequence. The TUSB2046B requires a power on reset pulse of between 100us to 3ms after 3.3-V (Vcc) reaches its 90%. We recommend an external RC circuit (15K pull-up resistor and 1 uF cap), please use this circuit to try to solve the issue. Anything less than 100 us is too short for the device and anything longer than 3ms can interfere with USB enumeration (mainly an issue for embedded systems).

    Regards

  • 0 in reply to Joel Jimenez0
    Prodigy 80 points

    Muy bueno,

    The  EXTMEM\ terminal to high and EEDATA pin to low fixed it.