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DP83848x PFBIN and PFBOUt

Mazen Matar
Prodigy 100 points
Other Parts Discussed in Thread: DP83848VYB

Hello,

I am designing the DP83848VYB/NOPB into a product.  There is a confusing part in the data sheet that I wanted to double check with someone before I continued.

In section, 7.2.1.3 Power Feedback Circuit, the guideline is "Pin 18 (PFBIN1), pin 37 (PFBIN2), pin 23 (PFBIN3) and pin 54 (PFBIN4) must be connected to pin 31

(PFBOUT),".  BUT, Pin 31 is NOT PFBOUT.

Wondering if anyone has worked with this device before? 

Thanks,
Mazen

  • 0
    TI__Mastermind 19780 points
    Hi Mazen,

    The datasheet description in section 7.2.1.3 is incorrect, please use figure 7-4 for a schematic example of how to connect PFBOUT(pin 23) to PFBIN1 (pin 18) and PFBIN2 (pin 37).

    This is a known typo and will be fixed in a future revision of the datasheet.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Prodigy 100 points

    Thanks for the quick reply Rob.


    Another concern I had was with the line-side TD+ and RD+ connections.  The datasheet shows them connected to the NON-dotted side of the transformer coil, where in the reference designs, and in all other designs I have worked on, the + leg of the signal was always connected to the dotted side of the transformer coil.  Please see attachment.Discrepency in the TI Datasheet vs Reference Designs.docx

    Not sure if it makes a difference for 10/100 type signals, but I figured I would check to make sure.

    Thanks,

    Mazen

  • 0 in reply to Mazen Matar
    TI__Mastermind 19780 points

    Hi Mazen,

    The connection to the transformer will not affect functionality. The connection will only change pulse polarity. MLT-3 signaling of 100BASE is polarity independent.

    The DP83848x has the ability to automatically detect and correct 10BASE signaling polarity inversion.

    Best Regards,