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LM25119: What limit the output current?

chentsu chung
Mastermind 6180 points
Part Number: LM25119
Other Parts Discussed in Thread: LM5119

Hi,

From TI.com, can see the Iout(max) of LM25119 is 40A.

As I know, the current limitation is all about MOSFET and Inductor, am I right?

Here are the question:

1. How this 40A be defined?

2. What limits the output current?

3. Can I use it support 40A+40A?

Thank you.  

  • 0
    TI__Mastermind 24075 points

    Hi Chentsu,

    You are right. The output current limitation is mainly from MOSFET and inductor. 

    It will be good to use LM5119 2phase for each 40A rail to achieve better efficiency,  low output ripple and thermal performance, but it is doable to use LM5119 for 40A+40A application.

    Below are a few things to be aware if one channel supports 40A current.

    1. LM25119 uses sensing resistor in series with low-side FET to sense current. The power loss on the sensing resistor needs to be considered to make sure the resistor will not burn.

    2. To support 40A+40A, MOSFET in parallel might be needed and the gate drive loss on LM5119 could be large. To reduce the power loss on LM5119, VCCDIS pin can be used to allow external voltage being applied to VCC1 and VCC2.  

    Thanks

    Qian

  • 0 in reply to Qian Chen
    Mastermind 6180 points

    Hi Qian,

    Got it ,thank you very much.

    May I ask another question? So how the Iout(max.) be defined in TI.com?

  • 0 in reply to chentsu chung
    TI__Mastermind 24075 points
    Hi Chentsu,

    LM514x is a controller. As you know, the current limitation is mainly from MOSFET and inductor.
    maximum current we suggested is for typical applicaiton. It does not mean the controller can not be used for higher current.

    Sorry, I'm not very familiar with LM514x parts.
    If you have further questoin on LM514x, I would suggst to submit a new post. Someone else will support it.

    Thanks
    Qian