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TUSB4041I: Regarding the VDD(1.1V) and Crystal

user5999038
Prodigy 40 points

Part Number: TUSB4041I

Hi all

I have a few quiestions to use this device.

Could you advice to me?

(1)Regarding VDD (1.1V)

In the dataseet, VDD of this device recommended the voltage with 1.1V typ (from 0.99 to 1.26V.)

Now, I want to use this device with 1.2V typ (from 1.13 to 1.31V).

In this case,  Do you have any problem? 

(2)Regarding Power Save

Now, the crystal for TSUB4041I did not oscillate only with the power supply and reset signal was released.

After the USB cable connected, the Crystal started to oscillate.

Is USB communicaiotn required for oscillating the crystal of TSUB4041I?

Please let me know if there is a setting terminal to oscillate the crystal continully only with power supply.

  • 0
    TI__Guru 64326 points

    Hi,

    1) I do not recommend exceeding the 1.26V for the VDD rail.

    2) Could you provide a waveform for clarification? The crystal should oscilate after GRST is released. there is no setting where the crystal will start with power supply. 

  • 0 in reply to Malik Barton57
    Prodigy 40 points

    Thank you for your answer.

    and sorry too late to reply,

    (1) I understand

    (2) Could you check the figure I attached 

          CH1 (BLUE) : VDD33

          CH2 (Light BLUE) :VDD

          CH3 (PURPLE)  : GRSTz

          CH4 (Light GREEN) :Xtal output

    And now I have the new question

    (3)Regarding VDD

        Could you see the same figure? 

        VDD(CH2) is drop to 0.8V between powered on and GRSTz released.

        Is this behaivor correct? 

     

  • 0 in reply to user5999038
    TI__Guru 64326 points

    Hi,

    This behavior is not correct for a proper power on reset. 1.1V should be stable before GRST is released. Could you zoom in on GRST release so that we can tell?

  • 0 in reply to Malik Barton57
    Prodigy 40 points

    (3) Regarding VDD

    It's resolved.

    Sorry, This drop of VDD(1.1V) is happend by ferrite bead. 

    I used the ferrite bead with High DC resistance (over than 0.05 ohm).

    See the new figure changed ferrite bead.