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LMH1228: Recommended EQ setting

Takahiro Saito
Expert 5465 points
Part Number: LMH1228


Hi team,

1. In the below condition, is the adaptive EQ mode recommended rather than manual mode?

    Datarate:        12Gbps

    Trace length:   0 ~ 20 inch

2. Datasheet says EQ can compensate up to 20 inch of trace length. Can this device support more than 20 inch of trace length?

3. Could you give me the recommended EQ value for 10inch and 30inch trace in manual EQ setting? 

Regards,

Saito

  • 0
    TI__Guru* 93570 points

    Hi Saito-San,

    1). Please note table 4 of the LMH1228 data sheet. Additionally, please note table Recommended Operating Condition table in the data sheet as well. We need to make sure source side transmit level is within recommended settings.

    2). This depends on the insertion loss of the PCB material used in customer application. I believe we should be able to handle 25 to 30 inches using 5-mills width FR4 material.

    3). Please note table for of the LMH1228 data sheet.

    Regards,, Nasser

  • 0 in reply to Nasser Mohammadi
    TI__Expert 5465 points

    Hi Nasser-san,

    Thanks.

    Datasheet table.4 says that EQ=0x90 is a recommend setting for 20 inch table.

    For 30 inch trace, is it a good start point for manual equalization level?

    Regards,

    Saito 

  • 0 in reply to Takahiro Saito
    TI__Guru* 93570 points

    Hi Saito-San,

    You can use 0x90 setting as the starting point.  Then you can fine tune this value by reading and optimizing HEO/VEO values.

    Regards,, Nasser