AM5728: USB 2.0 layout guide question

HAOTING WEI

Prodigy 40 points

Part Number: AM5728

Hi,

From layout guide, it indicated usb 2.0 can support up to 12 inch trace.

But the usb 2.0 signal in reference board from TI website only has ~4inch trace.

Is there any reference board with 12inch usb 2.0 signal that pass the compliance test?

Thanks.

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

There are two AM572x EVM boards: www.ti.com/.../TMDSEVM572X and www.ti.com/.../TMDXIDK5728

0 HAOTING WEI over 7 years ago in reply to Biser Gatchev-XID

Prodigy 40 points

Hi Biser,
I've downloaded 2 boards, but the longest usb 2.0 trace is around 4.5inch.
So, TI doesn't have a board with 12inch long usb 2.0 signal, right?

I'm curious about the maximum length in layout guide.
Because I do simulation for a usb 2.0 channel around 9" and it failed...
Don't know whether the ibis model from TI website has any prolem.

0 Biser Gatchev-XID over 7 years ago in reply to HAOTING WEI

TI__Guru**** 393215 points

I will ask the factory team for clarification. They will respond here.

0 HAOTING WEI over 7 years ago in reply to Biser Gatchev-XID

Prodigy 40 points

Hi Biser,
Any update for this question?
Thanks.

0 Biser Gatchev-XID over 7 years ago in reply to HAOTING WEI

TI__Guru**** 393215 points

I have escalated the request.

0 -DK- over 7 years ago in reply to Biser Gatchev-XID

TI__Mastermind 27720 points

Apologies for the delay.

We do not produce a customer board that incorporates 12" of USB trace. This value was obtained through simulation of the interface in conjunction with our internal USB PHY characterization process.

Please note: No two PCB designs are the same and it is not possible to state categorically that 12" can be supported on all boards in all configurations. Parasitic influences drive up insertion losses which will eat into the trace-length budget making it vital that all PCB designs be simulated prior to fabrication to ensure that sufficient margin exists to support the interface requirements. The closer you come to the interface limits, the more important the simulation results become.

0 HAOTING WEI over 7 years ago in reply to -DK-

Prodigy 40 points

OK. I've done the simulation. Just curious about the length limitation described in layout guideline.
Thanks.

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AM5728: USB 2.0 layout guide question