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LMZ23610: Low Efficiency by using the LMZ23610 power module.

Part Number: LMZ23610

Hi team:

Efficiency is very low by using the LMZ23610 power module.

Input voltage is 18 V, input current is 1.033 A.

Measured output voltage is 4.863, output current is 2.4A. Efficiency is only 62.8%. 

Operated at room temperature, chip's temperature was normal.

What are the reasons might cause the efficiency so low? Any way to improve it?

Best regards.

Shuo

  • Hi Shuo,

    Can you provide me the schematic and layout to understand your circuit? I ran a Webench design for Vin=18V,Vout=5V,Iout=2.4A and got a simulated efficiency of 88%.

    WEBENCH:https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=4EC22AB28D140725

  • Thank you so much for your reply.  I also use Webench design when I design the board, pretty much followed the design tool. The efficiency also shows 88% when I simulate it. I have attached my schematic. Any idea why the efficiency is too low?

  • Hi Shuo,

    Is C3 supposed to be a Cff? Just wanted to make sure that if it is meant to be a Cff, then it should be placed in parallel with R2 connected between Vout and FB.

    Also how are you measuring your input and output voltage? Are you measuring it at the pins of the module? I'd like to rule out any IR drop issues during measurement.

    The datasheet efficiency measurement is collected on the LMZ23610EVM. For your application of Vin = 18V, Vout = 5V, Iout = 2.4A, it should be ~85% efficiency following Figure 1 of the datasheet.