LM3489: LM3489 protection issue

Patrick Chen

Part Number: LM3489

Hello

Please refer to below waveform. While load increase to 0.5A, 5V output voltage will be pull down to 0V. Could I know what is the issue root cause? Thank you.

Ch1: Input , Ch2: output

Ch1: MosFET Gate , Ch2: output , no-load

Ch1: MosFET Gate , Ch2: output , load: 0.5A

Patrick

over 6 years ago

0 Timothy Hegarty over 6 years ago

TI__Guru 73952 points

Hi Patrick,

I forwarded your enquiry to the product expert.

Rgards,
Tim

0 Samuel Jaffe over 6 years ago in reply to Timothy Hegarty

TI__Mastermind 25590 points

Patrick,

Thanks for this information. It looks like the part is triggering OCP from the increased load before we expect it to. This is most likely due to noise coupling due to layout. Please try placing a 1nF cap in parallel with R184 (R connected to ADJ) as shown in the datasheet. If that does not solve or improve your issue please share the layout so I can take a look.

Thanks,

-Sam

Power management

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LM3489: LM3489 protection issue