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LM5141: LM5141RGER efficiency

Diego Rossini
Prodigy 80 points
Part Number: LM5141

Hi all,

I made a DCDC buck regulator, using the webench power designer, with LM5141RGER, I attach the design report. I use this DCDC converter with a voltage of 24V as VIN.

As you can see on efficiency graph, with a load of 2A and 24Vin, the efficiency should be about 95%. I tried on my PCB and with these condiction the efficiency is 83%.. Too low..

So I checked the part number of components, some signals, like HO, HOL, LO, LOL, but they seem all ok..
The heat dissipation is normal: only the mosfets and the inductance are more hot than the others components, and thy are at 32°C..

What can I check?
What can be the problems?
How can I do to improve the efficiency? I would like to reach the 95%..

WBDesign115 (1).pdfThank you in advance,
Have a nice day.
Diego.

  • 0
    TI__Mastermind 23845 points

    Hi,

    Are you using the same value of Rsense, and how about the inductor DCR (series resistance)?

    Is your switching frequency is the same as webench?

    You can also check whether you have a diode D1 the same as webench?

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    Prodigy 80 points

    Hi,

    Yes, Rsense is 7mohm, and the resistance of inductor is 5.5mohm.

    The frequency is 357.23 kHz, in the webench is 348.821.. The difference is small..

    D1 is the same...

    I have reduced R1, or R2, or R3, in order to reduce the rise and fall time, but nothing change;

    I have tried to reduce frequency, but is worse than the previous value..

    Have you got others ideas?

    Thank you,

    Diego.

  • 0 in reply to Diego Rossini
    TI__Mastermind 23845 points

    Hi,

    Are you using the same part number of MOSFET with webench? M1 and M2?

    Also how is your layout for the device?

    You can check the layout for an EVM as a reference

    Double check the layout of the MOSFET and power inductor since this is the power dissipating elements in the design

    IHow is your other load efficiency? Are they become closer to webench at higher load? 

    Thanks

    -Arief

  • 0 in reply to Arief Hernadi
    TI__Mastermind 23845 points

    Hi,

    I hope you have resolved your issue. For now i will close this thread, feel free to reply to open the thread. 

    Thanks

    -Arief