DS125BR800A: No clock output with DS125BR800A

Feng bin Su

Part Number: DS125BR800A

Hi team,

My customer is using our SATA/PCIE retimer DS125BR800A but there is no output clock measured at output of retimer.

The operating frequency is @1.6GHZ. The current swing is about 0.85Vp-p (such as the attached waveform), so they want to use the DS125BR800A to increase the swing from 0.85V to 1.3V. Please refer their circuit as below link. Could you help to check whether there is any problem with the hardware settings inducing no output issue? They are using pin mode of retimer. Thank for your kindly help.

https://txn.box.com/s/enxs0hpedgztzdxhrkvdhh50ecok9ace

over 5 years ago

0 Lee Sledjeski over 5 years ago

TI__Mastermind 43795 points

Hi,

I would replace the Ferrite bead on the VIN pin with a short.

I do not see any AC coupling on the high speed inputs and outputs of the DS125BR800A devices. AC coupling is required, are there capacitors in the signal lines on other schematic pages not shown in the attached schematic file?

Regards,

Lee

0 Feng bin Su over 5 years ago in reply to Lee Sledjeski

TI__Expert 8120 points

Hi Lee,

Customer's DC input voltage is 0.2V and Vp-p=0.8v. May I said it is the ac-coupling problem induuce no output problem?

Customer said they can remove the AC-coupling in other case.

0 Brian Zhou over 5 years ago in reply to Feng bin Su

TI__Guru** 123940 points

sorry, lee will be back after Thanksgiving.

0 Lee Sledjeski over 4 years ago in reply to Feng bin Su

TI__Mastermind 43795 points

Hi,

The AC coupling on the high speed inputs is required so the DS125BR800A can generate the input common mode it needs to work correctly. The device requires an input common mode voltage of ~ VDD to work correctly. This usually requires AC coupling since most devices do not have a common mode output of ~ 2.5V.

Regards,

Lee

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DS125BR800A: No clock output with DS125BR800A