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LM25066A: Limitation for higher current on 12V system power

Eric Wu58
Prodigy 20 points
Part Number: LM25066A

Hi Team,

The LM25066A is an ideal 12V hotswap solution for the use in server platforms, usually two external power MOSFETs (i.e. 5x6mm package) are used in parallel in our design to handle 12V main power for the system, since the power supplied by 12V main has increased constantly on new platforms because of instaneous peak power in turbo mode, I would know is there any limitation for the LM25066A to connect more MOSFETs in parallel for higher power delivery? Or any other solution is suggested.

Best regards,

Eric

  • 0
    TI__Guru 57737 points

    Hi Eric,

    The major issue/consideration with parallel Mosfet's is,

    • During start-up, hot-short, and start into short the MOSFETs are in saturation region (VGS close to VT and large VDS) and a single MOSFET will take all of the current. So, you need to find  Mosfet's which has SOA that will be able to withstand all the current for the desired Timer duration. If not, the timer duration will be reduced to operate the Mosfet within its SOA region.

    For detailed explanation, you can refer to section 2.4 in the below app note

    How much is your Maximum Load Current? What is your Maximum Output Capacitance ?

  • 0 in reply to Praveen GD
    TI__Guru 57737 points

    Hi Eric,

    The design calculator allows you to design for upto 6 Mosfet's in Parallel. You can take help of the Design Calculator to see if you have enough SOA/Plim margin for your design. We generally recommend the Margn to be > 1.5.
    If you have high Output Capacitance, you can opt for external soft-start control placing a capacitor at the Gate pin to reduce stress on FET's during startup.

  • 0 in reply to Praveen GD
    TI__Guru 57737 points
    Hi Eric,

    Do you have any more questions? if not, can we close this thread ?
  • 0 in reply to Praveen GD
    Prodigy 20 points

    Hi Praveen,

    I have no other questions about LM25066A, thanks.

    Best regards,

    Eric