DS90UB953-Q1: DS90UB953 : STP Rin+/Rin- trace length difference

bastien durban

Part Number: DS90UB953-Q1

Hello,

On the DS90UB953-Q1 (rev sept 2018) specification, it's written "Route the RIN– trace loosely coupled to the RIN+ trace for the length similar to the RIN+ trace length when possible.", but there is no constraint value about the trace lenght difference between Rin+ and Rin-, could you give the maximum value please?

Thanks,

Bastien

over 5 years ago

0 Hamzeh Jaradat over 5 years ago

TI__Guru** 108360 points

Hello Bastien,

there is no specs for the trace length matching. You just need to try to make them equal as much as possible. Exactly matching them is not possible.

Please see layout example on figure 59 in the 954 d/s.

0 bastien durban over 5 years ago in reply to Hamzeh Jaradat

Intellectual 295 points

Hello,

I think you're talking about figure 60 (STP) and not figure 59 (COAX), I was wondering about this as for CSI lane there is a constraint ( trace lenght difference < 5mils, figure 61).

So for you,100µm of trace length difference started from the connector is ok?

Thanks,

BR,

bastien

0 Hamzeh Jaradat over 5 years ago in reply to bastien durban

TI__Guru** 108360 points

Hi,

I am talking about figure 59. Is not your question about using Coax not STP, correct?

0 bastien durban over 5 years ago in reply to Hamzeh Jaradat

Intellectual 295 points

Hi,

It's for STP ( I realize i didn't mention it in the first message)

Thanks,

Bastien

0 Hamzeh Jaradat over 5 years ago in reply to bastien durban

TI__Guru** 108360 points

Okay, now it is clear.

You need to Keep differential intra-pair skew to max. 20 - 30 ps by ensuring trace lengths are matched.
You can calculate the allowed difference in length depending on your board materials. But if your sustem is running at 4Gbps data rate then 5 mils is a good number to use.

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DS90UB953-Q1: DS90UB953 : STP Rin+/Rin- trace length difference