LM25116: 36 to 24V converter incorrect output: board review

Srinidhi Krishnan

Part Number: LM25116

Hello,

We are undergraduate students on an engineering project team. We are trying to build a 36V to 24V converter that can take 36-42V input and output 24V at a max current output of 8A.

We have created a board that currently outputs about 18.5V, and drops significantly as the resistance of the connected load increases. We are unsure whether this is due to manufacturing issues or design flaws of the board.

We have attached the Altium schematic and PCB layout for the board below; we would really appreciate if you could review our design and help us troubleshoot our issues.

Thank you!

converterDesign.zip

over 5 years ago

0 Iven Su over 5 years ago

TI__Expert 8245 points

Hi,

Before your design, you can refer to official evaluation board and its design results on the user's guide:

Also, you can use the WEBENCH® Designer to help design your board. Hope it helps.

0 Srinidhi Krishnan over 5 years ago in reply to Iven Su

Prodigy 40 points

Hello,

We did use WEBENCH in our component selection, and used the schematic it provided as a baseline for our design. We also looked at the evaluation board, but were not able to find Altium PCB files to reference. With our board, we were mainly concerned about plane size as we prioritized reducing size. Are there minimums or other constraints we should be looking at?

Thanks!

0 Iven Su over 5 years ago in reply to Srinidhi Krishnan

TI__Expert 8245 points

Hi,

My recommendation is using 80mil width / 1oz thickness copper for 1A current. Thanks.

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LM25116: 36 to 24V converter incorrect output: board review