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LM5050-1: Can I parallel the mosfets?

Part Number: LM5050-1

Hi Folks,

I have 2 battery packs (25V) to be ORed for a new project. The max current can be as high as 50A. I've looked at the LM5050-1 part, but according to section 8.1.1 MOSFET Selection (paragraph 5c) the ON resistance is required to provide a voltage range of at least 22mV and no more than 100mV.  The lowest Ron mosfet I can find is 3.6milliohm which makes the max current = 27.77A (0.100V/0.0036 ohm).

Is there another part you'd recommend?  Or can I parallel the mosfets to reduce the effective on resistance?



  • Hi Richard,
    Yes, you can parallel MOSFETs for high current usage.

  • Hi Richard,

    For 50A application, we recommend LM74700 which is in preview stage currently.
    LM74700 can support 50A by parralleling MOSFETs.

    Let us know if you require circuit recommendations.

  • Hi Kari,

    Why did you suggested to use LM74700 instead of LM5050-1 for  a 50A  application?

    Can  the  LM5050-1 be used in a 40A application with parallel MOSFETs?

    I am going to find a proper ORing  FET controler for a 40A application, which can pass the 0.5KV surge test.

    Do you have any circuit recommendations for this application?

  • Hi Richard,

    Difference between LM5050-1 and LM74700 is that LM74700 has a better gate current to drive bigger MOSFETs for high current applications.

    LM5050-1 can do the job, except that turn on time is slow due to lesser gate current strength. Slow turn ON means, that the body diode of the MOSFET will carry the inrush current and the startup current untill the MOSFET is turned ON.

    Slow turn on time is good application which doesn't like current spike during fast FET turn ON. For example, when the MOSFET is turned ON with turn on time of 1us, output sees a jump of 0.6V in 100ns. With output capacitance of 100uF, current spike could be about 60A. If the upstream power supply doesn't support this much current, it could hit the current limit and cause a non-smooth startup.

    For 0.5kv surge protection with LM5050-1, refer to the TI design "".