Motherboard VRM output current limitation

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  • ssb2245
    New Member
    • Apr 2011
    • 1

    #1

    Motherboard VRM output current limitation

    Now I understand that the limit part for current output on a motherboard is partially to do with the pins from teh PSU 12v connectiona nd teh pins in the socket.

    But I want to talka bout the buck converter, the main VRM for the CPU power.

    I know MOSFETs on boards are rated from 20-50amps. My question is about the inductors(chokes) and how they limit current. i understand that they have 2 current ratings,
    Irms which is continuous current, and Isat which is saturation current. I know that once you exceed saturation current the inductor's core becomes flooded with magnetic flux and it loses inductance. Does the Isat and Irms limit the amount of current a MOSFET can output to the capacitor bank and then to the processor.

    Lets say the inductor in question has an Isat of 28a and Irma of 28A and the MOSFETs can otuput 40A per phase. Would this mean that each phase is limited to 28A?

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