TUSB211: Eye diagram issue

Patrick Chen

Part Number: TUSB211
Other Parts Discussed in Thread: TUSB217

Hello

Below is customer topology. If remove re-driver 1 just reserve re-driver2 on board, the eye diagram are below and looks bad. Has any suggestion how to pass eye diagram testing? Thank you.

CPU-->PCIE connector	9 inch
PCIE connector-->re-driver1	2 inch
re-driver1-->re-driver2	10 inch
re-driver2-->USB switch	8 inch
USB switch-->USB port	2 inch

No re-driver

level0 120ohm

level 1 2kohm

level2 3.9kohm

level 3 7.5kohm

Patrick

over 5 years ago

0 Brian Zhou over 5 years ago

TI__Guru** 123615 points

test procedure may not right. Pls refer to document SLLA392 at Ti.com

0 Patrick Chen over 5 years ago in reply to Brian Zhou

Mastermind 8875 points

Hello

Below is Customer test setup. They already test many USB eye diagram for the same test method and environment. But we still can not see any signal improvement from EQ0~EQ3 that looks no any function for it. Has any suggestion and how to pass eye mask?　

Thank you.

Patrick

0 Brian Zhou over 5 years ago in reply to Patrick Chen

TI__Guru** 123615 points

1: connect all device, test fixture first
2; power on all devices
3; host send USB HS test package
4: eye diagram measurement
if fail
5: stop USB HS test package
6: adjust AC setting
7: reset TUSB211.
8:host send USB HS test package
9:eye diagram measurement

0 Blake Kuo over 5 years ago in reply to Brian Zhou

Intellectual 290 points

Could we cascade two re-driver on the same signal path ?
If we do cascade design, how to adjust EQ efficiently for this two re-driver ?

Blake

0 Brian Zhou over 5 years ago in reply to Blake Kuo

TI__Guru** 123615 points

not suggest to use two redrivers on same trace, unless it's on cable.

Also suggest to use TUSB217 , it's much easier to debug

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TUSB211: Eye diagram issue