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DS280BR810: Questions for VOD LIM-min/Max

Kazuki Kuramochi
Genius 10485 points
Part Number: DS280BR810

Hello Expert,

Our customer has questions for DS280BR810 as below.

  1. Datasheet's VOD LIM-min/Max value means the output amplitude which is achieved by datasheet's test condition
    Then, Could we change output amplitude from 360mVpp(0x0B[4:0]=0x00, 0x0D[3:0]=0x0,0x0C[3:0]=0x0,0x06[0]=0x1,0x06[7:6]=0x3) to 1260mVpp(0x0B[4:0]=0x1F, 0x0D[3:0]=0x0,0x0C[3:0]=0x0,0x06[0]=0x1,0x06[7:6]=0x3) by only changing 0x0B register manually?
  2. If 1st question's understanding is correct, Does it mean can we configured  output amplitude as 31step(29mVpp/step)?
  3. For 0x06[7:6], could we regard these resister is same principle as 0x0B?

Would you answer for these questions?
I'm looking forward to haring back from you.

Best regards,
Kazuki Kuramochi

  • +1
    TI__Mastermind 36153 points

    Hi Kazuki,

    1) Yes, you can change output amplitude by just adjusting 0x0B for the appropriate channel.

    2) There are 32 different steps (0-31).  You can configure the output amplitude through these different steps, but please keep in mind that the increase in peak-to-peak amplitude does not increase linearly with each step.  I would suggest looking at Table 35 in the DS280BR810 programming guide.  If you don't already have access to this guide, you can request access from the product page, under the "Special Note" section by clicking "Request DS280BR810".

    3) Registers 0x06[7:6] are functionally similar to register 0x0B if there are no pre/postcursor FIR coefficients (registers 0x0C[3:0] and 0x0D[3:0] are 0).  However, if pre/post cursors are being used, than increasing 0x0B without also increasing the 0x0C and 0x0D will alter the amount of pre and post cursor de-emphasis.  Adjusting the driver VOD (0x06[7:6]) will change the output amplitude without impacting the amount of pre and post cursor de-emphasis.  To summarize, both driver VOD and FIR main cursor can be used to adjust amplitude, but adjusting the FIR main cursor may also impact the amount of pre and post cursor de-emphasis applied by the redriver.

    Regards,

    Drew

    .