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DS280BR810: TI 25G retimer/repeater application

Part Number: DS280BR810
Other Parts Discussed in Thread: DS250DF810, DS280BR820, DS250DF410

Hi Team,

 

1.       Please help to have some clarification concerning to my specific application (attached ). I considering to use Octal Repeater(ds280br820)/Retimer(ds250df810) part as single device for redrawing both CAUI-4 interface streams : on RX direction 4 differential pairs 25Gbi/s  and on RX direction 4 differential pairs 25GB/s. I don’t found in TI Data Sheet information same application for octal parts. All presented and recommended configurations are having dedicated Retimer/Repeater part for each direction Please explain if this limitation actually relevant because of possible inter channel coupling between TX and RX direction signals used in single octal device (I don’t found any information for this feature in Data Sheet).

2.       Please help to clarify if TI has device same to octal retimer ds250df810 but without embedded  decoupling capacitors on TX outputs.  

 

Thanks,

Shlomi

reach_extension_1.pdf

 

  • Hi Shlomi,

    There is DS250DF410 with external AC coupling caps. Please note, AC coupling caps are still needed. This part has 4 lanes which could be used for RX or TX. I believe this should meet your requirements. Do you agree?

    Regards,,nasser
  • Hi Nasser,

    The device DS250DF410 was recognized as option for my application. My question to TI was concerning to octal repeater/retimer application was concerned with using this type for replacing double quad device application:

     

    .       Please help to have some clarification concerning to my specific application (attached ). I considering to use Octal Repeater(ds280br820)/Retimer(ds250df820) part as single device for redrawing both CAUI-4 interface streams : on RX direction 4 differential pairs 25Gbi/s  and on RX direction 4 differential pairs 25GB/s. I don’t found in TI Data Sheet information same application for octal parts. All presented and recommended configurations are having dedicated Retimer/Repeater part for each direction Please explain if this limitation actually relevant because of possible inter channel coupling between TX and RX direction signals used in single octal device (I don’t found any information for this feature in Data Sheet).

    Please advise for this issue asap.

    Thanks,

    Shlomi

     

    reach_extension.pdf

     

  • Hi Shlomi,

    As long as cross talk or cross coupling is less than media insertion loss + 10dB, this would provide DS280BR820 with good enough SNR to run error free operation. In your diagram, you showed 10dB loss due to media and connector. So at minimum cross coupling should be less than 20dB. I believe using connector model and your pcb layout you should be able to provide/simulate even lower than 20dB isolation.

    Regards,,nasser