DS250DF230: Behavior when signals of different data rates are input

Hi Nishie,

I'm performing some bench testing on this setup. I'll provide an answer to your questions by EOD tomorrow.

Best,

Lucas

Hi Lucas-san,

Thank you for conducting the bench test. I am looking forward to your answer.

Best Regards,

Nishie

Hi Nishie-san,

I'm finishing up my bench test and will provide an answer shortly.

Best,

Lucas

Hi Nishie-san,

Unfortunately I ran into some challenges with my setup using a DS250DF230EVM, so I was not able to verify if I can also get CDR lock at 4.9152 Gbps when transmitting 9.8304 Gbps data. I do not find it surprising that the retimer achieved CDR lock in this situation as the configured and transmitted data rates are half rates.

What pattern are you transmitting when you see CDR lock in this situation?

Can you also share the following channel register values in your setup?

• 0x09, 0x18, 0x2F, 0x60, 0x61, 0x62, 0x63, 0x64

Yuta Nishie said:

Q3. When DS250DF230  is configured in 4.9152Gbps and lock to 4.9152Gbps data, then the input is seamlessly switched from 4.9152Gbps to 9.8304Gbps, does the device keeps lock state?

Yuta Nishie said:

Q4. Assume that 4.9152Gbps and 9.8304Gbps are sent alternately. If you lock at 4.9152Gbps and then change the setting to 9.8304Gbps (for example, in a short time after 100 ms), will you lock at 9.8304Gbps?

As it is not intentionally designed behavior to see CDR lock at twice the configured data rate, I don't have a clear answer to these questions. If the transition between data rates is truly seamless then I would expect CDR lock to be maintained, however I'm not sure how consistently the retimer could reproduce this behavior.

Do you have a measure of the delay when switching between 4.9152 Gbps and 9.8304 Gbps data transmission?

Best,

Lucas

Hi Lucas-san,

Thank you for your support.

I will confirm with the customer about the channel register value and a measure of the delay when switching data transmission. I will let you know when I receive the answer from the customer.

Best Regards,

Nishie

Hi Nishie-san,

Sounds good, thank you for your help communicating with the customer.

Best,

Lucas

Hi Lucas-san,

The customer is busy evaluating another device and has not been able to confirm it yet.

I think I will be able to respond after next year.

Best Regards,

Nishie

Hi Nishie-san,

Sure, you can let me know when customer has gotten the chance to answer my questions.

Best,

Lucas

Hi Lucas-san,

I was able to check the customer's register values.

Can you solve the problem with this content?

Best Regards,

Nishie

Hi Nishie,

These register settings are correct to configure 9.8304 Gbps and 4.9152 Gbps.

What pattern is the customer configuring when they see the CDR lock to a 9.8G signal while configured for 4.9G? If they are transmitting a PRBS signal, I'm not surprised that the retimer obtains lock in this situation because much of the content of a 9.8G PRBS signal looks like a 4.9G signal. It likely isn't possible to prevent the retimer from locking in this situation.

Best,

Lucas

Hi Lucas-san,

Thank you for your support.

I understand that the Retimer is locked.

I would like to ask you a more detailed question. Could you tell me your email address?

Best Regards,

Nishie

Hi Lucas-san,

Thank you for your friend request.

I want to click "This resolved my issue" but there is no button in this thread.

What should I do?

Best Regards,

Nishie

Hi Nishie-san,

I see, there appears to be a bug right now and I can't mark as "TI thinks resolved" either. I will close the thread internally and message you privately.

Best,

Lucas