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ONET1151L: ONET1151L High Modulation Current

Don Foong
Expert 4100 points
Part Number: ONET1151L

Hi Team,

Hope you can help to clarify the “high modulation current” mode. When it is enabled, how much is the modulation current changed for each setting ?

Is figure 30 meant for 'High Modulation Current' - Enabled ?

 

Thanks for looking into this enquiry.

Regards,

Don

  • 0
    TI__Guru* 93670 points
    Hi Don,

    Table 2 means when modulation current is enabled. Perhaps it would have been better if we called this column Modulation Current versus High Modulation Current.

    Figure 30 shows linearity of register setting versus actual modulation current.

    Regards,,nasser
  • 0 in reply to Nasser Mohammadi
    TI__Expert 4100 points

    Hi Nasser,

    Thanks for the reply. We have share your feedback with customer. However, customer have some findings that seem to them that contrary to CPENA and OCDIS setting. Can you help to verify below customer's comments is true ? Thanks.

    Thanks for the quick response. But we don’t think “High Modulation Current” is just “Modulation current”, for two reasons:

    1. It is clearly said below that it is capability change, not enable or disable;

    2. We set the CPENA and OCDIS as 0/0, and the eye is even better than 1/1. If 0/0 is modulation current disabled, how comes the better eye?

    Thanks and regards,

    Don

  • 0 in reply to Don Foong
    TI__Guru* 93670 points
    Hi Don,

    I am looking into this and will let you know in a couple of working days.

    Regards,,nasser
  • 0 in reply to Nasser Mohammadi
    TI__Guru* 93670 points
    Hi Don,

    I am checking with one of our designers on this. Customer noted CPENA and OCDIS as 0/0 they get a better eye opening. Is this optical or electrical eye diagram?

    Regards,,nasser
  • 0 in reply to Nasser Mohammadi
    TI__Expert 4100 points

    Hi Nasser,

    Customer feedback that is optical eye.

    Thanks and regards,

    Don

  • 0 in reply to Don Foong
    TI__Guru* 93670 points
    Hi Don,
    We've been discussing this with our designers.
    There is not a technical reason why CPENA or OCENA should be correlated with high modulation current. Our thought is that optical module is more optimized when setting these two bits to 2'b00.
    As it relates to the data sheet, we are going to revise these sentences in future revision of this data sheet to prevent this confusion.
    Regards,,nasser