LM5175: Unstable output at transition

William Jayson Nunez

Part Number: LM5175
Other Parts Discussed in Thread: PMP9490

Hi TI,

I am designing a 375W battery charger where input is 11-32V and output is 6-14V/25A for the battery. I am having problem during transition of buck-boost to boost. there is a loud audible noise since the pulse is unstable. but becomes stable once it goes to boost mode.

I reference my design from PMP9490.

Thanks and regards,

William

over 7 years ago

0 William Jayson Nunez over 7 years ago

Prodigy 50 points

I need also to control the output current (not using the internal constant current). I used the CV/CC loop.

0 Vijay86929 over 7 years ago in reply to William Jayson Nunez

TI__Genius 11490 points

Hi Jayson,

25A is kind of high for one phase. Other than that some common tips for improving the buck-boost performance are:
* increasing the injected slope (reduceing CSLOPE)
* increasing the Rsense (cycle by cycle current sense resistor)
* Using higher Cc2
* Beter sensing and layout for improved noise performance
regards

0 Blue sky over 7 years ago in reply to Vijay86929

Prodigy 30 points

Hi, Vijay :
It is very good tips.
But I do not know what is Using higer Cc2?

Regards.

0 Vijay86929 over 7 years ago in reply to Blue sky

TI__Genius 11490 points

Hi Blue,

Sorry about the confusion. The Cc2 is the term used in the datasheet (and other documents) for the high frequency compensation capacitor connected to the COMP pin of the controller.

Regards

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LM5175: Unstable output at transition