LM3150: The maximum output current for LM3150

Zhang Liang

Expert 2085 points

Part Number: LM3150

Hi,

We use the LM3150 for our power rail, we know the max. output current for LM3150 is 12A in datasheet,

we request the LM3150 for below spec.:Input voltage: 16-36V, output 5V/12A, and we find the output current can't reach the 12A max. and only 11A we can regulate,

and the inductance temperature is more than 80℃,

So please kindly review the schematic diagram and provide your comment how to adjust the spec.( like Rlim and so on), we can get the output current 12A based on our input voltage,

And please kindly advise how to calculate the max. output current thanks.

LM3150_EVOLUTION.pdf

5 months ago

0 EricLee 5 months ago

TI__Mastermind 46251 points

Hello Zhang

I think you already found the root cause. If you believe the current limit level is too low to handle 12A, please Increase RLIM or use a smaller Rdson MOSFET on the low-side, following the eq6 in the datasheet.

-EL

0 Zhang Liang 5 months ago in reply to EricLee

Expert 2085 points

Hi, Eric,

I simulate our design in the webence tool, I add the paramater but there are no reference design to create, so I think it is mean 12A max. current don't available for our design?

0 EricLee 5 months ago in reply to Zhang Liang

TI__Mastermind 46251 points

Hello Zhang

It means WEBENCH couldn't find suitable MOSFETs. It doesn't mean the LM3150 controller cannot handle 12A.

-EL

0 Zhang Liang 5 months ago in reply to EricLee

Expert 2085 points

Hi Eric,

Thanks, we can only rise the currrent to 11A and we have no idea why it can't reach the 12A max., and the inductance temperature is high, so plesae advise if this high temperauture will limit the output current? thanks.

0 EricLee 5 months ago in reply to Zhang Liang

TI__Mastermind 46251 points

Hello Zhang

Yes, the practical current limit level is decreased by increasing temperature because the RDSON of the MOSFET is increased by increasing temperature.

Please increase RLIM or use a smaller RDSON MOSFET on the low-side, and then check if any improvement.

-EL

0 Zhang Liang 5 months ago in reply to EricLee

Expert 2085 points

Hi Eric,

I will set the Rlim firstly;

BTW, the inductance temperature is high when the full load operation(11A or 12A), it is nromal or not?

0 EricLee 5 months ago in reply to Zhang Liang

TI__Mastermind 46251 points

Hello Zhang

The inductor temperature is the function of not only the IOUT, but also DCR and core loss.

Typically, the inductor temperature is high (above 60°C) at full load condition ~ 11A and 12A.

-EL

0 Zhang Liang 5 months ago in reply to EricLee

Expert 2085 points

Hi Eric,

Notes, thanks for your kindly support.

0 EricLee 5 months ago in reply to Zhang Liang

TI__Mastermind 46251 points

Thanks for choosing TI. Please feel free to contact us if you have any question.
-EL

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LM3150: The maximum output current for LM3150