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lm3488

mario soccini
Intellectual 730 points

3482.WebenchReportsServlet.pdfI create a design by webench. Now i have the prototype but i have serious problem with efficiency.The value of voltage out is ok but the efficiency at full load is 50%.  vin=24v  vout=120v  0.12A . I'm not sure about the Rfa about frequency.  

  • 0
    TI__Expert 6165 points
    Hello Mario,
    Low efficiency is most likely caused by high switching frequency, ~500kHz, a very large MOSFET, and may also be due to diode selection. The MOSFET shown is rated for use up to 25A while your maximum peak current needed for 0.12A output is ~600mA (with 20V input). Also, the diode’s forward drop is shown as 0.85V which may indicate a slow, junction diode. The fastest type in your voltage range is a carbide diode. If these are out of your price range, make sure that you are using an ultrafast recovery diode. If you are not comfortable continuing this conversation on a public forum, please email me at robert.blattner@ti.com
    Regards, Robert Blattner