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DP83848 Power Calculations

Andrea Ramos
Intellectual 975 points

I am doing worst case power analysis on the DP83848 in our application, which is standard 100BASE-TX with magnetic 1:1 transformer to a standard line.

I did read data sheet and also AN-1540 on power in use.

Am still confused about how much power will be dissipated within the DP83848 vs how much in the termination network.

The tables in AN-1540 break it out by center tap current, but that current will have some dissipation within the DP83848.

How can I calculate/estimate power loss in the DP83848 itself.

  • 0
    TI__Mastermind 31600 points

    Andrea,

    For purposes of a power analysis, I would break it down into two categories - current drawn from the center tap supply and current drawn from the device supplies (AVDD33 and IOVDD33).  This is what the application note is intended to communicate.  

    How are you planning to power the device?  Will the device and the center taps be supplied by one common supply or by two separate supplies?  In most applications, the two supplies are shared.

    Patrick

  • 0 in reply to Patrick OFarrell
    TI__Intellectual 975 points

    Thanks, Patrick.  Please see customer response:

    We supply all power from one supply.

    What is confusing me (I think I am making it more complicated than it should be) is trying to figure how much power is dissipated within the DP83848 versus how much power is dissipated or delivered through the Ethernet magnetics. Because I’m trying to predict how hot the device junction will get, this is important.

    Thanks for your help.