• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 102 subscribers
  • Views 634 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TMS320DM8168: Resistor value for USB0_R1

Kanae
Mastermind 9655 points
Part Number: TMS320DM8168

Hi Davinci support Team,

According to the DM816x datasheet (sprs614f.pdf: page 93), USB0_R1,
the USB reference resistor should be 44.2Ω ± 1%.
My customer' s design follows the datasheet, however the eye pattern
does not have any margin.
When it reduces the resistor value to increase the drive electric current,
the eye pattern increase the margin.

Question:
If customer will change the resistor value on DM8168 datasheet recommended,
what kind of issue will be happened?

Best regards,
Kanae

  • 0
    Intellectual 760 points
    Hi Kanae,

    This query has been forwarded to respective team.

    Regards,
    Prashant
    Pathpartner Technology Pvt. Ltd.
  • 0 in reply to Prashant A
    Guru 13620 points
    Hi,

    Can you refer to the following requirement for the USB2.0 EYE diagram test : http://testusb.com/HSEYE.htm

    Please check if the Fixture and connector requirements are met
  • 0 in reply to Dwarakesh Radhakrishnan
    TI__Guru**** 170625 points
    Hi Kanae,

    Only the value provided in datasheet is tested and verified by TI. Using any other value is not recommended and its impact to the board can not be predicted.

    See also if the below e2e threads will be in help:

    e2e.ti.com/.../165644
    e2e.ti.com/.../386602

    Regards,
    Pavel
  • 0 in reply to Pavel Botev
    Mastermind 9655 points

     

    Hi everyone,

     

    Thank you very much for your quick reply.

     

    >Dwarakesh R,

    Thank you for introducing the test environment.

    My customer product has been passed the USB test, but what you meant is

    my customer test result will be better if he uses your recommended test environment.

    Is my understanding correct?

    Actually my customer needs to know the effect when he changes the resistor value

    on DM8168 datasheet recommended; 44.2 ohm ± 1%.

     

    >Pavel,

    I have checked the e2e thread as references, there were no answers about the effects

    when changing the resistor value.

    However some persons have faced this problem.

    I will try to explain to my customer that TI has tested and verified

    only the value; 44.2 ohm ± 1%, provided in datasheet,

    and using any other value is not recommended and

    its impact to the board cannot be predicted.

    I hope my customer will be convinced by this explanation.

     

    Best regards,

    Kanae