• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 543 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.

DS92LV1021A: Power Supply Requirements

KAEDE KUDO
Expert 2700 points

Part Number: DS92LV1021A

Hello,

My customer has a question about DS92LV1021A.

[Q]

I have a question about the description of the following D/S.

`DVCC(AVCC) voltage level should be identical to the AVCC(DVCC) voltage level.`

How much is the potential difference between the above terminals allowed?

Also, if I configure the power supply terminal connection as follows, does not the above description of D / S be adhered to?

*Ferrite beads are inserted to separate DVCC and AVCC.

*The bypass capacitor is omitted in the picture above.

The background of the question is as follows.
Communication errors may occur if operating for a long time with the above configuration.
Improve it by removing ferrite beads and shorting them.

Considering that the potential difference between AVCC and DVCC is the cause of such operation, we are inquiring.

Best Regards, 

Kaede Kudo

  • 0
    TI__Genius 10250 points
    Hello Kudo-san,

    I don't have specific tolerance spec for the potential difference between the AVCC and DVCC. However, the arrangement shown looks good to me and should work fine.
    I just want to clarify something: are you saying that they actually tried removing the ferrite bead and when they did that the didn't see the errors anymore? Have they tried and different ferrite bead?

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    Expert 2700 points
    Hello Yaser-san,

    Thank you for your fast reply!
    OK, I will confirm with the customer about the comment you gave me.

    And below, I will describe what I recognize.
    * At first they did not insert ferrite beads.
    * When inserting ferrite beads by revision, reception error sometimes occurred.
    * Deleting ferrite beads improved the phenomenon.

    Best Regards,
    Kaede Kudo
  • 0 in reply to KAEDE KUDO
    Expert 2700 points
    Hello Yaser-san,

    They inserted ferrite beads by revising.
    There was no communication error before revising.
    Communication error has occurred only on board after revision.
    Removal of the ferrite beads on the revised board will allow it to operate properly.
    They have not confirmed the change in behavior by changing ferrite beads inserted.

    I am thinking as follows.
    The cause of this phenomenon is that a potential difference occurred between AVCC and DVCC due to insertion of ferrite beads.
    Therefore, it is a useful measure to remove the ferrite beads.
    However, the potential difference between AVCC and DVCC is not specified.

    Is my way of thinking appropriate?
    I need to explain to them why the reception error occurred and what kind of countermeasure is needed.

    Best Regards,
    Kaede Kudo
  • 0 in reply to KAEDE KUDO
    TI__Genius 10250 points
    Hi Kudo-san,

    The use of the ferrite bead is recommended and I am surprised the results were worse when using the bead. There shouldn't be any DC potential difference across the ferrite bead. Have they tried to measure it? Is it possible that it is a bad ferrite bead? Please ask them to tyr to replace it. If thing are working better in their case without the ferrite bead, it is really up to them to remove it.

    Regards,
    Yaser