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LM25069: hot swap design

Huang John
Prodigy 60 points
Part Number: LM25069
Other Parts Discussed in Thread: LM25066

Hi TI,

About hot swap design,
MOS layout could be as below?

thanks 

John

  • 0
    TI__Guru 57737 points
    Hi John,

    Do you have 9 Mosfet's in parallel - 6 placed vertically and 3 placed horizontally ?

    Regards,
    Praveen
  • 0 in reply to Praveen GD
    Prodigy 60 points
    hi Praveen,

    yes, 6 placed vertically and 3 placed horizontally.

    BR
    John
  • 0 in reply to Praveen GD
    Prodigy 60 points
    Hi Praveen,
    Does this placement affect the current balance?

    BR
    John
  • 0 in reply to Huang John
    TI__Guru 57737 points

    Hi John,

    The resistance path from Sense Resistors(Rs) to all Mosfet's is not symmetrical. The resistance in the path between  the Rs and FET's is different. This will cause inbalance in current sharing. Although the difference can be low as the Rs and FET's are close enough.

    One problem I can see probably is that there can be current crowding  in the area near bottom sense resistor. This will cause more heat which may eventually cause the FET's near that area to take less current. 

    Can you let us know your design Specs: Output Caps, Input Voltage, Maximum Load Current, operating Temp Max.

    Looks like you are operating at high load current. Why don't you consider LM25066 which interfaces with a low-cost external diode for monitoring the temperature of the external FET's. 

    Please click "This resolved my issue" button if this post answers your question.

    Regards,

    Praveen