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DS280DF810: VEO Lock Monitoring

Wesley He
Expert 6205 points
Part Number: DS280DF810

Tool/software:

Hi team,

Customer is using DS280DF810ABVR, set receiver adapt mode 2.When I write Reg_0x0a to reset CDR channel，sometimes the CTLE value adapts to 0x00, sometimes the CTLE value adapts to 0x04. The value of VEO will vary significantly depending on the value of CTLE. A good CTLE value ,VEO can reach up to 0x60. while a poor CTLE value ,VEO can only reach 0x3c. Therefore, I want to limit the value of VEO to be greater than 0x40 (200mV) before CDR stops adapting .I found Reg_0x6a, but the maximum VEO value it can set is 15 * 4 * 3.125mV=187.5mV, which does not meet my requirements .Is there any other way to limit the value of VEO to be greater than 0x40 (200mV) or 0x50 (250mV)?

Thanks.

Regards,

Wesley

  • +1
    TI__Mastermind 36623 points

    Hi Wesley,

    You are correct that register 0x6A controls the VEO lock threshold and 187.5mV is the maximum value that can be set.

    I have a couple thoughts in regards to this:

    • Is it possible to share the HEO values associated with the VEO values at CTLE 0x00/0x04?  I'm wondering if a different adaptation algorithm could help address this issue.
    • It appears this is a low insertion loss channel.  Will the customer always use a low insertion loss channel?  If so, they could set CTLE = 0.
    • The customer could try increasing the EOM timer from 5 to around 7-10.  This will help with any lower probability jitter that could be contributing to sub-optimal adaptation.
    • We have an optimized CTLE table that might help in this application.  I will share this with you over email.

    Thanks,
    Drew