TUSB216-Q1: eye diagram show difference between host mode and device mode

Chuqiang Wen

Part Number: TUSB216-Q1
Other Parts Discussed in Thread: TUSB216

Hi Expert,

My customer is using TUSB216-Q1 in their head unit project. Their system block diagram like below. The USB host in below screenshot is the SOC. The USB controller in SOC can be configured to host mode or device mode.

But they found a strange phenomenon when performing the eye diagram test. The result shows some difference between USB controller in host mode and device mode. USB device mode have better eye diagram result.

When performing eye diagram test in host mode, we see the low level of ENA_HS.

Do you have any ideas about this phenomenon?

Thanks!

Ethan Wen

over 1 year ago

0 Josh Baik over 1 year ago

TI__Mastermind 19321 points

Hi Ethan,

Can you check the CD and HS_ENA pins during the eye diagram test?

Regards,

Josh

0 jianfang zhang over 1 year ago

Prodigy 50 points

Hi, Josh

We have test the CD and ENA_HS pin as following. The USB of Head unit works in the high-speed mode.

1.Eye diagram test when Head unit in the host mode, ENA_HS=Low, CD=High.

2.Eye diagram test when Head unit in the device mode, ENA_HS=High, CD=High.

3.U disk test when Head unit in playing mode, ENA_HS=High, CD=High.

Have you ever encountered a situation where ENA_HS is low when testing the HOST eye diagram? And how to solve this situation?

Jeff

0 Josh Baik over 1 year ago in reply to jianfang zhang

TI__Mastermind 19321 points

Hi Jeff,

Please refer to this application note (SLLA593). You might need to follow Host Mode Testing procedure.

Regards,

Josh

0 Pan Peter over 1 year ago in reply to Josh Baik

Prodigy 20 points

We found below table in your application note (SLLA593):

Device and Embedded Host HS testing mode are not supported by TUSB216, right?

What about TUSB216-Q1? Currently we use TUSB216-Q1.

Thanks

0 Pan Peter over 1 year ago in reply to Josh Baik

Prodigy 20 points

Hello Josh,

In the spec we can see TUSB216 supports up to 5-m cable length.

We would like to know if there is any restriction on the position of TUSB216 to achieve 5-m cable length？

If TUSB216 is placed near the USB controller, what cable length can TUSB216 support up to?

0 Josh Baik over 1 year ago in reply to Pan Peter

TI__Mastermind 19321 points

Hi Pan,

TUSB216-Q1 is feasible like TUSB216.

It would be desirable to place as close as possible to the connector. Please refer to Detailed Design Procedure section in datasheet for placement guideline.

Regards,

Josh

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TUSB216-Q1: eye diagram show difference between host mode and device mode