DS320PR1601: Gen5 Redriver

SHEKHA SHOUKATH

Intellectual 520 points

Part Number: DS320PR1601

Tool/software:

Hi,

I am using DS320PR1601, for our new project.

I am attaching the stack up our board.

I got the DS320PR1601 EVM board details from TI.

Also we referred its layout and stack up file.

We understood that symmetry is followed in the stack up, while in ours we were not able to follow the symmetry.

Is it necessary to maintain symmetry in stack up?

Also based on the current stack up in order to attain 85ohm impedance, trace width and spacing should be7mils.

But we can achieve only 84.758ohm in top, while in bottom 85.423ohm.

While routing track width of 7mils, we need to have track width difference of 2mil near the Redriver IC.(ie 5mil near IC pin), is that okay?

KIndly provide your valuable suggestions.

Thanks and Regards,

Shekha Shoukath

3 days ago

0 Undrea Fields 3 days ago

TI__Genius 11360 points

Hi Shekha,

Maintaining symmetry isn't a requirement but recommended. Keeping the trace impedance within tolerance is a requirement, we suggest 85 ohms +/- 5%(10% if board manufacturer cannot control within 5%).

narrowing the trace to 5mil into the IC is acceptable and common practice due to routing constraints.

You can also reference the following app note: https://www.ti.com/lit/pdf/snla426

Regards,

Undrea

0 SHEKHA SHOUKATH 11 hours ago in reply to Undrea Fields

Intellectual 520 points

Hi,

Actually, we did the layout design based on this document only.

We have routed TX/Rx lanes on top, L8 and Bottom. (Our card is 10 layer)

Refclk is routed on top and and L3.

Thanks and Regards,
Shekha Shoukath

0 Undrea Fields 59 minutes ago in reply to SHEKHA SHOUKATH

TI__Genius 11360 points

No issues with that. I would just recommend to add GND stitch vias next to high-speed signal vias.

Regards,

Undrea

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DS320PR1601: Gen5 Redriver