DS280DF810EVM: Unable to Achieve CDR Lock at 14.025 Gb/s

Chenxuan Cui

Prodigy 40 points

Part Number: DS280DF810EVM
Other Parts Discussed in Thread: DS280DF810,

Tool/software:

Hello,

I am evaluating the DS280DF810 retimer using the DS280DF810EVM.

According to the datasheet, the DS280DF810 supports:

÷1: 20.2 – 28.4 Gb/s
÷2: 10.1 – 14.2 Gb/s
÷4: 5.05 – 7.1 Gb/s

Test Result:

CDR lock works correctly at 28.05, 26.56, 25.78, 24.33, 13, 12, 11, 10.3125, and 10.3 Gb/s.
CDR fails to lock at 14.025 Gb/s, even though this is inside the specified ÷2 band.

Question:

Why does the device fail to achieve CDR lock at 14.025 Gb/s, despite being within the datasheet’s ÷2 lock range?

Any insights would be greatly appreciated.

4 days ago

0 Evan Su 4 days ago

TI__Mastermind 18405 points

Hi Chenxuan,

We have assigned a team member to help with your question. Monday is a US holiday so the response may be slightly delayed.

Best,

Evan Su

0 Drew Miller1 1 day ago in reply to Evan Su

TI__Mastermind 35723 points

Hi Chenxuan,

Can you share some details on how you are configuring the retimer data rate?

Thanks,

Drew

0 Chenxuan Cui 16 hours ago in reply to Drew Miller1

Prodigy 40 points

Hi Drew,

I select the data rate on the CDR tab, set the Channel Select, then set to Manual Mode, set the data rate to various values(14.025 Gbps in the case), then click "Write Rate Regs".

+1 Drew Miller1 14 hours ago in reply to Chenxuan Cui

TI__Mastermind 35723 points

Hi Chenxuan,

There is a bug in SigCon Architect GUI for rates >13 Gbps that should be divide-by-2 where SigCon Architect GUI does not treat these rates as divide-by-2.

Please set rate to 28.05 Gbps and set the divider to divide-by-2.

Thanks,

Drew

+1 Chenxuan Cui 7 hours ago in reply to Drew Miller1

Prodigy 40 points

Problem solved ! Thank you !
that’s a strange bug. Hopefully the new version will fix it.

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DS280DF810EVM: Unable to Achieve CDR Lock at 14.025 Gb/s