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I am designing a simple buck converter to drive 9 V, 3 A LED. Supply can vary between 20 and 30 V. I used the TI Power Designer Tool to calculate the inductance value and other parameters. Here is the schematic:

enter image description here

enter image description here

After driving the load, everything is fine except that the inductor is getting heated to almost 85°C.

My PCB has to go into an enclosed box so this is not OK.

Strange thing is, the MOSFET is not getting hot at all, so the gate driving is fine, I guess. I have no clue why only the inductor gets heated in a buck converter.

Please suggest what factors concerning the inductor I should look into.

Vin : 20-30V switching frequency : 350kHz

Inductor HCM1A1307V2-330-R : Datasheet

Mosfet SI_4288DY : Datsheet

Diode SS54 : Datasheet

Driver IR2110 : Datasheet Here is the calculation screenshot of TI tool: enter image description here

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  • \$\begingroup\$ Data sheet links for the inductor and silicon devices are required. \$\endgroup\$
    – Andy aka
    Jan 8, 2022 at 11:34
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    \$\begingroup\$ What are the values of: Vin, switching frequency, inductor maximum current, inductor peak to peak ripple current? \$\endgroup\$
    – bobflux
    Jan 8, 2022 at 11:46
  • \$\begingroup\$ What switching frequency are you using? Please put this detail and the links into your question and not in comments. This isn't a forum. \$\endgroup\$
    – Andy aka
    Jan 8, 2022 at 11:46
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    \$\begingroup\$ @VishweshGM Please edit the part numbers and links into your question. Readers are not expected to dig through the comments for such important information. \$\endgroup\$
    – marcelm
    Jan 8, 2022 at 11:50
  • \$\begingroup\$ Why does your driver chip 0 volts connect to the MOSFET source (thus shorting the output to ground). Please show a more consistent circuit where all the components used are in 1 schematic with no ambiguity and, all the power rails are clearly indicated. Why haven't you added the DS for the MOSFET driver in your question. \$\endgroup\$
    – Andy aka
    Jan 8, 2022 at 12:01

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enter image description here

From page 14 of the datasheet.

Your temperature rise is much higher than expected so I'd check that you're not saturating the inductor. A 65°C temperature rise above ambient suggests that you're running at 7.5 A.

The DC resistance is listed as 40.8 mΩ. 7.5 A will cause a dissipation of \$ P = I^2R = 7.5^2 \times 0.04 = 2.25\ \text W \$.

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