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DP83822I: Link up time

Kuramochi Tadahiko
Guru 28715 points
Part Number: DP83822I
Other Parts Discussed in Thread: TLK105

Hi,

My customer is evaluating DP83822 to replace TLK105.

It seems that the link-up time of DP83822 is longer than 1.5s compared to TLK105.

They are compared link-up time and they set "Fast Link-Up in Parallel Detect" to "0" for both devices.

What is this difference caused by?

Best Regards,

Kuramochi 

  • 0
    TI__Expert 5425 points

    Hi Tadahiko,

    Just to double-check, has the customer physically tested the link-up time and seen the 1.5 sec difference?

    Having auto-MDIX and auto-negotiation enabled can increase link-up time. Longer length cables can also cause an increase in link-up time. You can disable those features and/or shorten cable length for faster link-up time. The "Fast Link-Up in Parallel Detect" should not have any effect on the link-up time.

    Regards,

    Adrian Kam

  • 0 in reply to Adrian Kam
    Guru 28715 points

    Hi Adrian-san,

    My customer observed the link-up time on waveforms and compared them with the same pin configuration, cable(length), register values, and connecting device.

    What should we check for anything else?

    I write each register value.

    --------------------------

    【TLK105】

    (REGADR,VAL)

    0x00000000 : 0x00003100                 

    0x00000001 : 0x00007849                 

    0x00000002 : 0x00002000                 

    0x00000003 : 0x0000a212                 

    0x00000004 : 0x000001e1                 

    0x00000005 : 0x00000000                 

    0x00000006 : 0x00000004                 

    0x00000007 : 0x00002001                 

    0x00000008 : 0x00000000                 

    0x00000009 : 0x00007802                 

    0x0000000a : 0x00000126                 

    0x0000000b : 0x00001009                 

    0x0000000c : 0x00000000                 

    0x0000000d : 0x00000000                 

    0x0000000e : 0x00000000                 

    0x0000000f : 0x00000000                 

    0x00000010 : 0x00000002                 

    0x00000011 : 0x00000108                 

    0x00000012 : 0x00000000                 

    0x00000013 : 0x00000000                 

    0x00000014 : 0x00000000                 

    0x00000015 : 0x00000000                 

    0x00000016 : 0x00000100                 

    0x00000017 : 0x00000041                 

    0x00000018 : 0x00000400                 

    0x00000019 : 0x00008061                 

    0x0000001a : 0x00000000                 

    0x0000001b : 0x0000007d                 

    0x0000001c : 0x000005ee                 

    0x0000001d : 0x00000000                 

    0x0000001e : 0x00000102

    0x0000001f : 0x00000000

     

     

    【DP83822】

    0x00000000 : 0x00003100

    0x00000001 : 0x00007849

    0x00000002 : 0x00002000

    0x00000003 : 0x0000a240

    0x00000004 : 0x000001e1

    0x00000005 : 0x00000000

    0x00000006 : 0x00000004

    0x00000007 : 0x00002001

    0x00000008 : 0x00000000

    0x00000009 : 0x00000002

    0x0000000a : 0x00000126

    0x0000000b : 0x00001009

    0x0000000c : 0x00000000

    0x0000000d : 0x00000000

    0x0000000e : 0x00000000

    0x0000000f : 0x00000000

    0x00000010 : 0x00000002

    0x00000011 : 0x00000108

    0x00000012 : 0x00000000

    0x00000013 : 0x00000000

    0x00000014 : 0x00000000

    0x00000015 : 0x00000000

    0x00000016 : 0x00000100

    0x00000017 : 0x00000041

    0x00000018 : 0x00000400

    0x00000019 : 0x00008061

    0x0000001a : 0x00000000

    0x0000001b : 0x0000007d

    0x0000001c : 0x000005ee

    0x0000001d : 0x00000000

    0x0000001e : 0x00000102

    0x0000001f : 0x00000000

    --------------------------

    Best Regards,

    Kuramochi

  • 0 in reply to Kuramochi Tadahiko
    TI__Expert 5425 points

    Hi Tadahiko,

    Looking at the register dump, there does not seem to be anything noteworthy that would cause this link-up time difference. Considering the two devices have different architectures, there may be differences in the link-up time as a result.

    I also have the following questions:

    1. What is the cable length the customer is using?
    2. What is the customer's goal of conducting this comparison? Is there a link-up time requirement for the system that they are trying to achieve?
    3. Is this 1.5 second difference seen across multiple attempts/runs? Is it something the customer sees consistently? What link-up times are the customer seeing for each device?

    Regards,

    Adrian Kam