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TUSB214: The function check

Lisa Xu
Intellectual 345 points
Part Number: TUSB214
Other Parts Discussed in Thread: TUSB211, TUSB216I

Dear TI Team:

we have tusb214 and Tusb211 design in our project,

I found TUSB214 both have AC boost and DC boost function for USB HS applicaiton.

Could you share

1. What case will use AC boost function(e,g, TUSB211 just have AC boost function) ?

2. And what case will use DC boost function?

3. Whether can disable DC boost function,juse use AC boost function in TSUB214?

Best Regards!

Lisa

  • 0
    TI__Genius 17505 points

    Hi Lisa,

    Lisa Xu said:

    1. What case will use AC boost function(e,g, TUSB211 just have AC boost function) ?

    2. And what case will use DC boost function?

    The TUSB21X line of redrivers do not have any means of differentiating when a signal needs AC or DC boost. These redrivers detect when a signal is connected (indicated via the CD pin) and when a HS signal is being used (indicated by the ENA_HS pin), and when both are detected, both AC and DC Boost are enabled. Yes, the TUSB211 only has AC boost functionality, while the TUSB214 and every redriver past the TUSB211 has AC boost functionality as well.

    Lisa Xu said:
    3. Whether can disable DC boost function,juse use AC boost function in TSUB214?

    Unfortunately, you can not disable DC Boost while still enabling AC Boost. You can adjust the settings of each individually to set DC Boost to the lowest setting while setting AC Boost to the needed level.

    Please let me know if you have any other questions.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Intellectual 345 points

    Hello Ryan:

    Thanks for your reply,

    And for question 1 & question 2, 

    Question 1: AC boost is used when USB AC signal is impacted by the long trace or other signal interference, Am I right?

    and this can be checked by USB eye-diagram.

    Question 2: DC boost is used when USB signal pass through a USB cable to cause DC common voltage loss, Am I right?

    And It seems there is no DC common voltage test when do USB test, How do I know our USB signal common voltage is impacted?

    And How do I know what DC boosts level is suitable?

    Best Regards

    Lisa

  • +1 in reply to Lisa Xu
    TI__Genius 17505 points

    Hi Lisa,

    Lisa Xu said:

    Question 1: AC boost is used when USB AC signal is impacted by the long trace or other signal interference, Am I right?

    and this can be checked by USB eye-diagram.

    Yes, both these attributes of an eye are affected by these conditions, and can be checked with an eye diagram. Additionally, our later redrivers, like the TUSB216I, come with further compensation for jitter that may come from longer cable lengths.

    Lisa Xu said:

    Question 2: DC boost is used when USB signal pass through a USB cable to cause DC common voltage loss, Am I right?

    And It seems there is no DC common voltage test when do USB test, How do I know our USB signal common voltage is impacted?

    No, DC boost does not affect the DC common voltage. It only affect the DC voltage of the eye. The picture below indicated what sections of the eye are affected by AC or DC boost.

    Lisa Xu said:
    And How do I know what DC boosts level is suitable?

    The best way to do this is to set our redriver at the lowest level and measure the eye diagram. From there, you can see if the level provides enough margin while not exceeding the maximum threshold, or if it needs to be adjusted to a higher level.

    Please let me know if you have any other questions.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Intellectual 345 points

    Thanks Ryan, It is really useful.