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AM6548: AM65x PCIe differential impedance control question

Thomas Yang55737
Expert 4601 points
Part Number: AM6548

Team,

In  AM65x “Application Note: High-Speed Interface Layout Guidelines”, the requirement for PCIe differential impedance control of AM6548 is 95Ω±5% , in AM57x and K2, the value is ±10% ,

Customer want to know the reason, and can they use ±10%, as the stricter standard will lead to a significant PCB cost increase.

-Thanks

Thomas

  • 0
    TI__Mastermind 27860 points

    Thomas,

    The AM65x recommendations are an attempt to accommodate the use of USB3 and PCIe GEN3 on the same channel as is done on our EVM. However, the use of PCIe GEN3, which requires tighter impedance control, has since been deprecated by Device Erratum i2104.

    If this customer is only using PCIe, and only in GEN1 and/or GEN2 mode(s), a target differential impedance of 100 Ohms (+/- 10%) for this channel can be supported. Please ensure that the resulting design is simulated prior to manufacturing as tighter impedance control may be required depending on board-specific variables such as channel length, PCB substrate material, connectors, link partner, vias, etc.