LM3150 15W power breakdown

Jonas Laridon

Other Parts Discussed in Thread: LM3150

Hi everyone,

I have made a Buck convertor based on the LM3150. It works exactly as expectd untill it reaches an output power around 15W, than the controller just burns, some smoke apears and it smells bad. I have been searching online if there is some kind of power limit on 15W, but didn't find anything. The convertor should be able to deliver upto 12Amps, so 15W is not a lot.

The output voltage can vary between 5,12 and 20V by changing a switch which enables extra feedback resistors.

Here are my schematic and PCB:

I hope there is someone who can help me :)

Jonas Laridon

Master student Industrial engineering

KULeuven

over 10 years ago

0 Florent Boico over 10 years ago

TI__Intellectual 1775 points

Hi Jonas,
What is your input voltage? Are the FETs intact when the LM3150 is destroyed?
I would start looking at the switch node for voltage overshoot when the high side FET turns ON with high output current.
I hope this helps,Florent

0 Marc Davis-Marsh over 10 years ago

TI__Genius 10115 points

I would take a look at the input voltage pin 2 of the controller.

From your layout the bypass capacitor 0.1uF is very far from the controller.

Try replacing Cbyp with a 4.7uF.

Then add a 0.1uF next to the controller (near Cvcc) to better bypass the controller input voltage itself.

Then just to be extra safe. Place an aluminum electrolytic across your input terminals to damp any LC resonant tank that is formed from long input leads from your power supply to the ceramic input capacitors.

Regards,

Marc

0 Jonas Laridon over 10 years ago in reply to Marc Davis-Marsh

Prodigy 50 points

Thank you! I applied the changes and it works fine now!

Power management

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LM3150 15W power breakdown