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DS125BR820: DS125BR820 application issue.

Hugo Liu
Genius 5095 points
Part Number: DS125BR820

Hi Sir,

Our customer Block diagram as below.

Power on system can be run PCIe gen 3, but Run for some time down to Gen1 speed.

For this application have any concern? or any suggest share for me?

Hugo

  • 0
    TI__Mastermind 43795 points

    Hi Hugo,

    I do not have any specific issues with the PCIe topology shown.  Do you know the attenuation characteristics associated with each channel segment.

    For this type of application I would recommend to start testing using a relatively low CTLE and VOD setting on the DS125BR820.  

    Do you know the TX FIR settings of the other components in the system?

    Thanks and Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Genius 5095 points

    Hi Sir,

    if connector & PCB trace & cable Loss is 15~18dB, Through the way of DS125BR820,
    How many DS125BR820 units In series?

    Hugo

  • 0 in reply to Hugo Liu
    TI__Mastermind 43795 points

    Hi Hugo,

    I would only recommend one (1) DS125BR820 be used on the PCBA channel and one (1) DS125BR820 be used on the PCBB channel as you have shown in the block diagram.  If the channels on either side of the IDT device are just ~ 15-18 dB, I would recommend to use CTLE "Level 2" and VOD "Level 3" in the datasheet.

    We do not recommend cascading multiple repeaters within a single PCIe channel.

    What are the current DS125BR820 settings?  It is possible the links are over-equalized.

    Regards,

    Lee