WEBENCH® Tools/LM3150: low current

hyunchul cho

Prodigy 45 points

Part Number: LM3150

Tool/software: WEBENCH® Design Tools

Hello, I have made a power supply using LM3150.

My english is not that good.

The problem with the design is that it seems that the output current is severely limited.

The design was made for 8V and 5A and the limit of the unit is actually around 1A.

I have used Webench.

Input Voltage : 14 ~ 24V

Output Voltage : 8V

Ouput Current Max. : 5A

Switching frequency : 440KHz

Ouput : 8V @ 0.5A (SW Pin)

Ouput : 8V @ 1.5A (SW Pin)

The only changes compared to the Webench BOM were:(Yellow)

Regard

over 8 years ago

0 Arief Hernadi over 8 years ago

TI__Mastermind 23845 points

Hi,

Do you have the layout available? It could be you got some noise in the system

Thanks
-Arief

0 hyunchul cho over 8 years ago in reply to Arief Hernadi

Prodigy 45 points

Thank you for your advice

I will try again with the LM3150 EVB.

Thanks

0 YangZhang over 8 years ago in reply to hyunchul cho

TI__Genius 11085 points

Please also check your bench supply current limit. If the current limit is too low, supply voltage will drop quickly and cause mal function.
-Yang

0 hyunchul cho over 8 years ago in reply to YangZhang

Prodigy 45 points

I used EVB PCB to assemble the parts like the attached circuit.

But it also had the same fault.

So I changed the circuit to 8V at 7A using webench and it worked fine.

However, the same problem occurs when applied to my layout.

Maybe there is a problem with the layout.

thanks

0 Arief Hernadi over 8 years ago in reply to hyunchul cho

TI__Mastermind 23845 points

Hi,

It seems that the location of RFB2, RFB1 and CFF is quite close to the SW node trace (RLIM)

Can you move all the feedback components (RFB2, RFB1 and CFF closer to the CSS side? The FB node is quite sensitive and long trace could cause it to pickup some noise.

Thanks

-Arief

0 Arief Hernadi over 8 years ago in reply to Arief Hernadi

TI__Mastermind 23845 points

Also, you can try to reduce the RFB2 and RFB1 by a factor of 10 to improve noise immunity.
RFB1 to 1k
RFB2 to 12.4k

Thanks
-Arief

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WEBENCH® Tools/LM3150: low current