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Original question:

LMR36015: LMR36015FBRNXR

LMR36015: LMR36015F

George Thaliath
Prodigy 40 points
Part Number: LMR36015

We are currently using LMR36015BRNXR/BRNXT on our desings, When we change it to LMR36015FBRNXR/FBRNXT the power looses on the chip goes up by about 0.5W - 

All we have done is just replace the chip on the board and left all other parameters as is. Is there any way to keep this loss less or are we missing some thing?

Regards, 

  • 0
    TI__Mastermind 22226 points

    Hi George

    Can you please share your operate condition ?Vin range and Vo, Io. 

     LMR36015FBRNXR/FBRNXT is FPWM version while LMR36015BRNXR/BRNXT  is not. At light load, FPWM version will keep fixed frequency to ensure small voltage ripple while the other one will decrease frequency to keep high frequency at light load.

    So it's normal that at light load, LMR36015FBRNXR/FBRNXT will have lower efficiency than LMR36015BRNXR/BRNXT. But at normal load, these two should have no difference.

    Hope that helps.

    Best regards.

  • 0 in reply to Gui He
    Prodigy 40 points

    Hi Gui,

    The input voltage is 48V and the output is 22V  50mA nominal with peak consumption of  up to 600mA in once case and 48V to 3.3V with about 120mA consumption.  From what you have suggested is there any way I can get the  efficiency better on the FPWM version ? 

    The question is because the temperature on the chip versions vary by about 10 to 15degC which is huge in our application at the load we are operating. Or can we say for the FPWM version will manage it self if the temperature gets too much on it and change frequency to keep its life up?

    Regards, 

  • 0 in reply to George Thaliath
    TI__Mastermind 22226 points

    Hi George

    Please let me check and give you feedback again.

    Thank you.

  • 0 in reply to George Thaliath
    TI__Mastermind 22226 points

    Hi George

    FPWM does has larger power loss than PFM mode device under light load. Bu the total power loss and the temperature rise should not be very high .There would be no way to reduce this loss.

    Both FPWM and PFM has the OTP (over temperature protection ) which enters into hiccup mode when the Tj reaches TSD. But I think the Tj is far lower than TSD in your application.

    Best regards