LM5157: Load characteristics of lm5157

masaya.kato

Part Number: LM5157

I am building a circuit that uses LM5157 to boost the voltage from Vin: 5V to 12V and Vout: 13.5V (Iout=1A).
When the load characteristics were confirmed through actual measurements, the characteristics were as follows.

A voltage drop of about 0.5V was observed between no load and 1A load.
Is the above behavior normal for an IC?

Also, is it possible to eliminate the voltage drop during load by adjusting the peripheral circuits?

Input voltage: 12V fixed

負荷		出力電圧
0	mA	13.530V
100	mA	13.531V
200	mA	13.531V
300	mA	13.526V
400	mA	13.421V
500	mA	13.351V
600	mA	13.253V
700	mA	13.206V
800	mA	13.117V
900	mA	13.043V
1000	mA	12.987V

over 2 years ago

0 Moritz over 2 years ago

TI__Mastermind 18755 points

Hi,

Thanks for using E2E.

This problem might be related to your circuit. Can you share your schematic please?

Best regards,

Moritz

0 masaya.kato over 2 years ago in reply to Moritz

Prodigy 10 points

Hi. Moritz-san
Thank you for your reply.
Below is the circuit diagram. Please check it.

0 Moritz over 2 years ago in reply to masaya.kato

TI__Mastermind 18755 points

Hi Masaya,

The schematic seems to be ok. The only thing i found is, that the phase margin might be too low with your compensation network.

Please try to adjust the compensation according to the quickstart calculator, to get a phase margin of at least 60 degrees.

https://www.ti.com/tool/download/SNVR511

Can you also please send scopeshots of the output voltage, the input voltage, FB and switchnode in low output current condition as well as in 1A load condition?

I am looking forward to hearing from you.

Best regards,

Moritz

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LM5157: Load characteristics of lm5157