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Is the DP83848 compatible with a 2.5V MAC?

Jamaal_Charles
Genius 3245 points

Other Parts Discussed in Thread: TLK106, TLK105

Hello,

I see that the DP83848 is a single supply, 3.3V part.  The TLK106 looks similar, but with an optional core dual supply.   Can either work with a 2.5V MAC?

Thank you!

  • 0
    TI__Genius 14317 points

    Hi Jamaal,

    I looked at the input level specs for both devices:

    - For the TLK106:Vih = 2 V min, Vil = .8 V max  For 2.5 V CMOS logic: Vol max = .4 V, Voh min = 2.0 V  So, the TLK106 will likely work with a 2.5 V MAC input but beware that worse case there could be almost no noise margin for logic 1 inputs.

    - For the DP83848: I don't see Vih, Vil specs. just Input SDthon = 1 V max pp diff and SDthoff = 200 mV pp diff (both are threshold specs) Based on these alone it looks like 2.5 V logic might be OK

    Based on the Data Sheet statements, it looks like both devices are designed for 3.3 V MAC interface.

    I'll see if I can get the device engineers to comment.

  • 0 in reply to Jeffery Pfarr
    TI__Genius 14317 points

    Hi Jaamal,

    Just got htis from our Design Eng. folks:

    We are planning for the following support for TLK105/6:

    1)      2.5V VDDIO option for MII/RMII

    2)      1.8V VDDIO option for MII

    For each, the VDDIO buffer spec will be changed accordingly (current load will be reduced from 4mA to 2mA, threshold will be updated).

    Once these modes are supported we will release an application note. Look for device Release sometiime in the first half of this year.

  • 0 in reply to Jeffery Pfarr
    TI__Mastermind 31600 points

    Jamaal,

    Just to close the loop on this, the DP83848 does not support a 2.5V MAC interface.  Amongst the 10/100 DP83xxx devices, the DP836x0 devices provide support for a 2.5V MAC interface.  As noted above, the TLK105/6 would also be a good choice, especially if you want the smaller footprint. 

    Patrick

  • 0 in reply to Patrick OFarrell
    TI__Mastermind 31600 points

    Hi,

    I have moved your post to the Ethernet forum.  To help with better supporting and tracking your future questions in Ethernet, please post any new Ethernet related questions into this forum.

    Thanks!

    Patrick