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DS125BR800A: Limiting mode of DS125BR800A

John Liu59
Intellectual 2735 points
Other Parts Discussed in Thread: DS125BR800A

Dear,

In the datasheet, there is table7, Mode pin can set different driver characteristics, could you please help explain what the difference between the four different types?

if we set the Mode to 0, it is the "limiting" driver characteristics, we want to know if EQ can be set in this mode?

Thanks.

  • 0
    TI__Mastermind 43795 points

    DS125BR800A modes.

    Mode = 0  (Limiting Mode)

    This mode gives the driver much more voltage gain.  So that even a very small signal on the input will generate a full amplitude voltage swing on the output.

    Mode = F (Default)

    This mode uses an internal rate detect to determine if the data rate is "5G or less" or "8G or higher".  It is primarily for PCIe applications.  Lower datarates will get Mode = 0 and higher datarates will get Mode = 1

    Mode = 1  (Non-Limiting Mode

    This mode has low voltage gain - approximately 1.3:1 so many of the low frequency input signal characteristics are transferred to the output.

    CTLE equalization can be set in any of the Modes.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    TI__Intellectual 2735 points
    Hi Lee,

    Thanks for your clear explanation.
    In the datasheet, Table4m, there is note1 shows" the de-emphasis levels are available in SAS-3/PCIE gen3 modes when mode=1"
    I want to know in SAS/SATA 1.5/3/6Gbps mode, is there still de-emphasis function?

    Thanks.
  • 0 in reply to John Liu59
    TI__Mastermind 43795 points

    Hi John,

    Yes, the DE function will still work at the lower rates as well.

    Regards,

    Lee