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LM5146-Q1: hot for no load

Kaileh
Intellectual 620 points
Part Number: LM5146-Q1

Hi Sir 

We follow LM5146-Q1-EVM12V to design a daughter board 

But this daughter board is very hot for no load (reach to 70 degree) ,please kindly help to check this issue 

0.05A efficiency : Daughter board is  20% ,EVM is 43.2%

0.5 efficiency : Daughter board is 68% ,EVM is 82%

1A efficiency : Daughter board is 79% ,EVM is 88%

Test Video

Schematic and laytout

LM5146Q1-TEST.pdf

P-CAD-B.pdf

  • 0
    TI__Guru 57555 points

    Hello

    Here are my thoughts:

    1. Please check your design values with the calculator on the product page for this

    device.

    2. With your FET values in the calculator, check what efficiency it calculates and compare.

    3. Are you measuring board temp or FET temp, or controller temp?

    4. Are you testing with sync?  Try without sync to use DEM mode.

    5. What size is your board compared to the EVM.

    6. The EVM may have better FETs and inductor than what you are using.

    7. Be sure that the FETs are well soldered to the heat sink planes; SW, GND, and VIN.

    Thanks