LM5118: Inductor Overheating

Hi Bhanu,

thank you for using the E2E forum.

Can you share some more details:

- type of the inductor

- some scope plots of the Switch nodes (left and right from the inductor)

- Output voltage: AC couple to see how the stability is

- is there a difference if input is lower or higher than the output (Buck or BuckBoost mode)

Best regards,

 Stefan

Hello Stefan,

                     Currently our oscilloscope is not working

The inductor we have used is ETQ-P5M101YGC

Series catalog (panasonic.com)

It overheats in both buck and boost mode

Thanks

Hi Bhanu,

the inductor should be OK for 0.8A load but with 4 A it will be going into saturation.

So this should be replaced.

Buy as you see already a high temperature increase at 0.8A some scope plots would be really helpful.

I could not properly see the used output caps but it looks like this are really small.

It also looks like your compensation can become instable in BUCK mode with a phase margin of 20Degree

You can use the quickstart tool from the product page to check this.

Best regards,

 Stefan

Hello Stefan,

                      All the values of output capacitors are as per the TI webench design tool. we have output capacitor of 470nF and 15uF(Electrolyte).

Here you can see the layout on the PCB board. We have used 30um copper.

Thanks

Hello Stefan,

                      Any update on this thread?

Thanks

Hello Bhanu,

As we did not hear back from you, I expect that your issue is solved and I close this thread. Please post below if you have further question or start a new thread.

Best regards,
Brigitte