LM25088: If add load, LM25088 output would be drop

Eric Shen42

Part Number: LM25088

Dear TI:

My customer use LM25088, Vin=24V, Vout=12V, when no load, the output is 12V, but when there is 1A load, the output would be drop to 9V, and when the load increase, the voltage drop more big.

Can you help to analyze the LM25088 problem? Thanks!

over 5 years ago

0 shaohua liao over 5 years ago

Prodigy 20 points

Thank you.

I add a description of the phenomenon：The waveform of SW is very mixed。

0 shaohua liao over 5 years ago

Prodigy 20 points

If the load is connected, the power supply ripple on the input is very large！

0 Samuel Jaffe over 5 years ago in reply to shaohua liao

TI__Mastermind 25590 points

Shaohua,

Sorry for the delay.

Ripple on the input leads me to believe the input capacitor C11 may not be placed close to Q10 and U17 (FET and diode). Please check to make sure this capacitor is close in order to form a small current loop.

Other possible reasons for instability:

Rramp seems too small. Try 150k to 200k.
Recompensate. You can also increase inductance in your recompensation.
Check to make sure the layout aligns with the layout guidelines in the datasheet.

-Sam

Power management

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LM25088: If add load, LM25088 output would be drop