LM3150: LM3150 switching between 5.5V and 7V using reference design

Chris Jones25

Part Number: LM3150

I used the TI Power Designer and put in 12V minimum, output 5V 15A and used the LM3150 reference design. I imported it into Eagle and layed out the board and have assembled 3 of them and they all exhibit the same behavior. Measuring output I get 5.5V to 7V oscillating over about 2-3 seconds. The 4 large caps aren't installed, so ignore those. Any ideas?

over 7 years ago

0 Arief Hernadi over 7 years ago

TI__Mastermind 23845 points

Hi,

I ran your condition into webench. Are you see the oscillation only at higher current?
Seems like your component matches webench but the RLIM on webench is 2.15k ohm instead of 887 ohm on your schematic

Thanks
-Arief

0 Chris Jones25 over 7 years ago in reply to Arief Hernadi

Prodigy 220 points

Here's a screenshot showing the 866 on RLIM. I was checking voltage with a volt meter, no load when I posted. I just connected a 1 ohm panel resistor which should create a 5A load and the same voltage swing but this time M1 started smoking.

0 Arief Hernadi over 7 years ago in reply to Chris Jones25

TI__Mastermind 23845 points

Hi,

Do you have layout for your design? It could be that it needs more heatsinking area on M1 or there is sensitive nodes that need to be taken care of. Such as placing all the CIN closer to the FETs.
EVM userguide is normally a good start to check the proper layout for the device
www.ti.com/.../lm3150-500eval

Thanks and i hope that helps
-Arief

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LM3150: LM3150 switching between 5.5V and 7V using reference design