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DP83867IR: LED Strap connection question

Gabriel Xu
Intellectual 2145 points

Part Number: DP83867IR
Other Parts Discussed in Thread: AM3352

Hi teams

My customer is using DP83867 with AM3352 in a new project(They use Marvell's solution in the past. Below is their question:

  1. Do we have any application note or guideline about the register and strap connection configuration? 
  2. DP83867 have several LED PIN, these pins can also be used as strap detection. The datasheet shows the connection about MODE1/MODE2/MODE4 but didn' give the MODE3 connection.
  3. If we don't need the LED indicator function could we use 2 resistors to create wanted voltage level to finish strap connection without LED diode?
  4.  How to determine the clock skew parameter? 

  • 0
    TI__Expert 5670 points
    Hi Gabriel,

    1, 2, 3. Can you refer to section 8.5.1 Strap Configuration in datasheet? There is a link in this section to "Configuring Ethernet Devices with 4-Level Straps application report (SNLA258)", which has all the information you're looking for.

    4. Which clock are you asking for the skew?

    Regards,

    Hung Nguyen
  • 0 in reply to Hung Nguyen92
    TI__Intellectual 2145 points
    Hi Nguyen
    I have read that application note, but i didn't found any relative section about LED and strap multiplexing configuration.
    Especially for Mode 3 configuration.
    I also want to know if the LED indicator is not needed, could we directly connect the resisotor only to finish strap configuration?
    The skew i am talking about is the RGMII clock time skew.
    Thanks
  • 0 in reply to Gabriel Xu
    TI__Expert 5670 points
    Hi Gabriel,

    If the LED indicator is not needed, you can directly connect the strap resistors to the LED pin.

    Output clock skew can be observed on the oscilloscope. Input clock skew is typically measured on ATE.

    Regards,

    Hung Nguyen