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LMR23625: LMR23625

Gadi Lieberman1
Prodigy 80 points
Part Number: LMR23625

Hi,

The system did not accept a schematic in my previous post.

I use the LMR23625CQDDARQ1 in a typical application.

The layout is according to recommendations in DS.

Input voltage = 24V.

Output voltage = 5V

Output current = 300mA.

The DC/DC, L15 and C163 heat up to 55 degrees Celsius.

Please suggest solution!

  • 0
    TI__Mastermind 25590 points
    Gadi,

    Please share the layout as well as the part numbers for L15 and C163.

    How are you measuring these temperatures?

    -Sam
  • 0 in reply to Samuel Jaffe
    Prodigy 80 points

    Hi Sam,

    L15 - Pulse Electronics' PA4332.222NLT.

    C163 - TDK C1608X5R1H684K080AB.

    I measured the temperature with a thermocouple, on top of the components.

    Please see the attached file that contains the layout of the DC/DC.

    I can send the Mentor pcb file, too.

    Best regards,

    Gadi

  • 0 in reply to Gadi Lieberman1
    TI__Mastermind 25590 points

    Gadi,

    Thanks for this information.

    The component placement looks good! I'd recommend moving C167 as close as possible to the IC (VIN and PGND) but other than that it looks good.

    The GND plane is where most of the IC heat will escape. You can improve this by:

    • Extending the GND plane downward
    • Moving L15 to the right a bit and extending the GND plane upward
    • Removing all thermal reliefs on high-current pads (like the GND plane of the IC, the pads on C163...)
    • Double check that there's no thermal relief on the thermal pad of the IC
    • Add vias to move heat from the top layer to other GND planes on other layers

    You could also extend the VOUT plane to help the inductor relieve some heat. It's strange that you're measuring an increased temp on C163. This should not get very hot unless the board is very hot or there is lots of ripple voltage. Check to make sure the output is stable (not too ripply, check the switch waveform to make sure it's a constant rectangular wave).

    -Sam

  • 0 in reply to Samuel Jaffe
    Prodigy 80 points

    Sam,

    thank you for your prompt reply!

    Gadi