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DS125DF1610: How to manually set the data rate and do CDR bypass

Part Number: DS125DF1610
Other Parts Discussed in Thread: DS110DF1610,

Dear Team,

I want manually set the data rate to 11.3Gbps and follow the guide configuration but fail to have the 11.3Gbps.


  1. Does there any other registers which I need to take care of for the configuration?
  2.  Could you also guide me the method for CDR bypass configuration? 
  3.  Is there a programming guide for DS110DF1610? If yes, I need it through e-mail. Thanks a lot for the help.

Best Regards,

Tess Chen

  • Hi,

    May I have some update for the question above? Thanks!

    Best regards,

    Tess Chen

  • Hi Tess,

    Thanks for your patience.

    1) There are a couple additional registers I would recommend writing to in order to configure 11.3Gbps.

    First, please select the appropriate channel to make the writes to.  This can be done by setting the appropriate value to registers 0xFC and 0xFD.  It is also possible to broadcast settings to all channels by setting register 0xFF[1] to 1.  Tables 11 and 12 in the DS125DF1610 datasheet detail channel selection.  Regardless of which channel you select, please also ensure that 0xFF[0] = 1 in order to ensure that all writes are done to channel registers instead of shared registers.

    To set 11.3Gbps, start by making the register writes in the table in your initial post, then follow the writes below.

    Register      Write       Mask         Comment

    0x2F           0xE0       0xF0         Set first and second group to divide by 1

    0x0A           0x0C       0x0C         Assert CDR Reset

    0x0A           0x0C       0x00         Release CDR Reset

    2) In order to bypass CDR, please see Table 39 in the programming guide linked below.

    3) There is not a programming guide specific to the DS110DF1610, but there is a programming guide that covers several other DS1xxDFxxx retimers.  The vast majority of it will be directly applicable to the DS110DF1610 as well.  Please find it linked here: Programming Guide



  • Hi Drew Miller1:

    I have some questions about CDR bypass.

       1)  According to the CDR bypass setting of Table39, it does not work on DS110DF1610 and DS125DF1610 chips, but set the values of the following two registers, THE CDR bypass of DS125 chip is enabled, and the CDR bypass of DS110 chip is disabled

    REG 0x09 [5] = "1" //Enable Override Output Mux

    REG 0x1E [7:5] = "000" //Select RAW data (CDR Bypass)

       2) Now I want to know if DS110 needs to configure other registers besides these two.The rate I need to pass is 3.072Gbps, because DS110 does not support this rate, I need to set it to RAW mode

    Best Regards,


  • Hi zhangzhenq,

    I am not sure that I understand your problem correctly. Can you please confirm that my understanding below is correct?

    • CDR bypass settings in Table 39 are working for DS125DF1610
      • This is the expected
    • CDR bypass settings in Table 39 are not working for DS110DF1610
      • This is unexpected

    Also just double checking, are you selecting a channel using 0xFC, 0xFD, and 0xFF prior to using the settings in Table 39?


  • hi Drew Miller1,

    As you understand, the same configuration of CDR bypass works for DS125, but not for DS110.

    I've seen it. Channel selection is configured correctly.

    When testing the service on the DS110, it was found that there was a signal input displayed on the meter, but the signal synchronization was lost



  • Hi Zhang,

    Thanks for clarifying this issue.  I am looking into this and will get back to you with an update tomorrow.



  • Hi Drew Miller1,

    I have successfully configured the CDR bypass on the DS110, I have configured an extra 0x3E register, now MY Settings are as follows:

    reg        val        mask

    0x0A     0x0c      0x0c

    0x09     0x20      0x20

    0x1e     0x00      0xe0

    0x3E    0x43      0xff

    0x0A    0x00      0x0c



  • Hi Zhang,

    I'm glad to hear you got it working.