DS100DF410: Does signal detect cause device to attempt to lock CDR

Zach Kimble

Part Number: DS100DF410

Hello,

If I have CDR locked and the retimer is successfully transmitting data and then the transmitting device loses power, what will happen when the transmitting device regains power and begins transmitting data again? Will the retimer attempt to relock CDR automatically when the retimer detects a signal or do I need to manually do a CDR reset?

Thank you!

Best regards,

Zach Kimble

over 1 year ago

0 Evan Mayhew over 1 year ago

TI__Mastermind 19452 points

Hi Zach,

The retimer CDR will attempt to lock again automatically when the upstream device powers and transmits valid data. I have seen some edge cases where the CDR state machine may get stuck during the adaptation process, in which case a manual CDR reset may be necessary to acquire lock.

Thank you,

Evan

0 Zach Kimble over 1 year ago in reply to Evan Mayhew

TI__Intellectual 1135 points

Hi Evan,

Thank you for your response! Do you know what would cause the CDR state machine to get stuck during the adaptation process? I have seen that when the signal is more degraded it seems to fail to lock more often.

Best regards,

Zach Kimble

+1 Evan Mayhew over 1 year ago in reply to Zach Kimble

TI__Mastermind 19452 points

Hi Zach,

I share your observation for the degraded signal cases - it seems the more adaptation is needed to acquire lock, the more often CDR will struggle to consistently lock. In these cases, resetting the CDR will allow the adaptation process to iterate through CTLE/DFE/... values again until an optimal combination is found for lock.

Thank you,

Evan

0 Zach Kimble over 1 year ago in reply to Evan Mayhew

TI__Intellectual 1135 points

Thank you Evan!

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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DS100DF410: Does signal detect cause device to attempt to lock CDR