DP83867IR: all four pairs trace length should be same?

Hisao Uchikoshi

Part Number: DP83867IR

Hi Experts,

DP83867 can support four pairs MDI interface with magnetic. Each pairs of TD_P and TD_N trace length should be same. Should we keep all four pairs trace length be same?

Regards,

Uchikoshi

over 6 years ago

0 Geet Modi over 6 years ago

TI__Mastermind 26320 points

Hi Uchikoishi-san,

Please refer to layout guidelines in datasheet.

Regards,

Geet

0 Hisao Uchikoshi over 6 years ago in reply to Geet Modi

TI__Genius 15240 points

Hi Geet,

I can find below comment but cannot find each pairs length.

Within the differential pairs, the trace lengths must run parallel to each other and matched in length. Matched lengths minimize delay differences, avoiding an increase in common-mode noise and increased EMI.

Please see below fig.

My question is if we should all of a, b, c and equal?

Regards,

Uchikoshi

0 Geet Modi over 6 years ago in reply to Hisao Uchikoshi

TI__Mastermind 26320 points

Hi,

Yes, they are also expected to be equal.

Regards,

Geet

0 Hisao Uchikoshi over 6 years ago in reply to Geet Modi

TI__Genius 15240 points

Thank you for your reply.

Can I ask why they are to be equal?

There are some restriction to trace these to be equal so we want to know the reason.

Regards,

Uchikoshi

0 Geet Modi over 6 years ago in reply to Hisao Uchikoshi

TI__Mastermind 26320 points

Hi Uchikoshi-san,

This is to keep the signal delay same across the pairs.

Regards,

Geet

0 Geet Modi over 6 years ago in reply to Geet Modi

TI__Mastermind 26320 points

Hi,

I am closing this thread. Incase you need further assistance, please open new thread and provide reference to this thread.

Regards,

Geet

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DP83867IR: all four pairs trace length should be same?