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TPS92520-Q1: About the TPS92520 efficiency

qinlei
Intellectual 310 points
Part Number: TPS92520-Q1

hello，

i have one question about the TPS92520 efficiency  ,i would like to know Why is the efficiency relatively low under light load conditions？ 

As the load increases, efficiency improves, but in the end, efficiency decreases again when the load increases. Why is this？

  • 0
    TI__Mastermind 18535 points

    Quilei,

    This is expected behavior.  There are some losses that are fixed in the converter just due to operation of the device.  As the output power is lowered, those fixed losses become a larger fraction or portion of the losses thus the efficiency will go down.  This is a very typical efficiency curve and is true for most converters.  It is also common to see efficiency drop a bit at higher loads because at higher currents the dissipation in the FETs increase and because of the increase in dissipation the FETs get hotter, which means Rdson of the FETs increase thus losses go up.  Selection of both the high side and low side fets can be optimized for a single condition but because we have a fix size FET for both the high side and low side FETs you will see the curves will change with different conditions.  All these plots are very typical.  If you want to see how losses change with conditions and see where the losses change, then you can use our power dissipation calculator to see where the losses change.  There are a lot of apps note out there that explain the different losses in a buck converter and I leave it up to you to educate yourself on those loss mechanisms.  

      TPS92520-682 - ECU_Efficiency_Estimation_12142021.xlsx

    -fhoude