• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 3 answers
  • Subscribers 33 subscribers
  • Views 387 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DS125MB203: DS125MB203 how to set register for 10G-KR under IIC mode

user5848839
Prodigy 210 points
Part Number: DS125MB203

Hi

I use DS125MB203 in my design. I want to use 10G-KR under IIC mode. I set register as below list. It can work. Please help review my register and schematic and give me some suggestion. Thanks!

  • 0
    TI__Guru* 93670 points

    Greetings,

    I believe your register settings should work and looks fine. Please note to enable SMBus register access we need to first set Reg 0x06[3]=1'b1.

    Reviewed this schematic and please note some comments below:

    1). I am not sure why we have R120, R121, R122,R123,R126,and R127. Device has onboard 100-ohm back termination.

    2). Device requires or it is better to provide AC coupling on high speed signals. I don't see AC coupling Caps on S_OUT high speed signals.

    Regards,, Nasser

  • 0 in reply to Nasser Mohammadi
    Prodigy 210 points

    Hi Nasser

    I check in my design. Your suggestion is already in my design. 

    I don't put R120, R121, R122,R123,R126,and R127 in board.  It aslo don't work. I try put R1438 for raise the mode pin voltage.  it also don't work. 

    Please help suggestion what else can cause this problem. Thanks!

  • 0 in reply to user5848839
    TI__Guru* 93670 points

    Greetings,

    To look into this further, you can put the device in pin mode and set MODE to KR. Please set EQ and DEM settings to minimum and increase as needed. Eventually you may need to put scope probe and check signal quality.

    Regards,, Nasser

  • 0 in reply to Nasser Mohammadi
    Prodigy 210 points

    Hi Nasser

    My old design is put device in pin mode with CPLD. It is can work. Now i change my design for save cost. I want to use device in IIC mode and without CPLD. Please help for your suggestion. Thanks.

  • 0 in reply to user5848839
    TI__Guru* 93670 points

    Greetings,

    1). Instead of CPLD, you can hard wire or strap different pins - in pin mode. This way you do not need to use a CPLD.

    2). You can first make sure pin mode is working. Then switch to I2C mode and read registers. It is possible one of the settings defined by pin mode may not be set correctly in I2C mode. Please note, once I2C is enabled EQ, de-emphasis, and mode pin functionality are controlled through default registers. It is possible default register settings may not be the optimum or the same as pin mode settings.

    Regards,, Nasser