MP4576 power dissipation

DC-DC Power Converters
1

Hi, I’m considering the use of MP4576 to convert from 48Vdc to 24Vdc. The maximum output current consumption is 0.2A which is under the MP4576 maximum limit of 0.6A.
However, I’ve seen on the datasheet that the maximum continous power dissipation is 2.78W. So, in my case there would be 24V*0.2A = 4.8W which exceeds the value given in the datasheet. Should I consider the use of a heatsink? Is there other DC-DC converter that suits better for my requirements?

Thank you in advance.

Almudena

2

Get a demo and try it out. You seem a little unclear about the power dissipation issue. These converters are 90%+ efficient. So with an output power of 4.8W the power loss in the converter would be more like 0.48W. It isn’t as bad as you think.

3

Thank you very much for your help. I will consider MP4576 for my design.
In order to complete the design, I’ve tried the online DC-DC design tool and the complete design differs from datasheet. Here you can find attached the tool results:

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In datasheet, it is recommended an input capacitor of 22uF or 47uF (high output voltages) and the online design only requires 2x2.2uF.
For setting the output voltage, in datasheet is is recommended R1 value about 41 kohm and R4 is 20Kohm. However, online tool gives R1 of 10k and R4 equal to 0R.
I’m not sure which values I should take into account (datasheet or DC-DC online tool)
Thank you in advance.
Best regards.

4

Hi,
Apologies on the late reply, Thank you for utiliizing MPS Forum.

I went through this to see what the issue was. The simulation will assume ideal case, its better to follow the datasheet. You need to consider the loop bandwidth with R3/R1 sizing.

  • For R3/C5 arrangement of A2, I would recommend going with A1 arrangement.
  • Also, populate the polarized cap C4 on the schematic
  • I think the model assumes ideal input, therefore, C1 caps is 2.2, It should be higher.
  • Because of your operational spec, your output can be in DCM mode with the schematic you have shown.
  • You may also download the DCDC designer for desktop version

For future reference:

  • You may refer to my values here as well.

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Kind Regards,
Nouman