TPS54821 Output Ripple

Prescott Siao

Other Parts Discussed in Thread: TPS54821

Hi Team,

My customer are designing the 8A solution with TPS54821 from 12V to 1V, they had test with EVB with DCC mode (60% load to 120% load, 60% load with 500uS, 120% load with 500uS), the ripple noise cannot reduce to 50mV, even we added couple huge MLCC.

We use the EVM to do the test.

Can you please give some suggestions on this?

Thanks.

Prescott

over 9 years ago

0 JohnTucker over 9 years ago

TI__Guru**** 191445 points

Do you have a waveform that demonstrates your issue?

0 Prescott Siao over 9 years ago in reply to JohnTucker

TI__Intellectual 2220 points

Hi John,

We used 0-8A dcc-mod freq 1KHz on EMV .

Please help to give dome comments.

thanks.

Prescott

0 JohnTucker over 9 years ago in reply to Prescott Siao

TI__Guru**** 191445 points

That is only about +/- 60 mV voltage deviation. That transient response looks rather good already. If you need to decrease it further you may need to add a lot of additional capacitance, then re-compensate the loop. You may need as much a 2600 uF to keep the voltage within +/- 25 mV.

0 Prescott Siao over 9 years ago in reply to JohnTucker

TI__Intellectual 2220 points

Hi John,

Do you have the value of the output cap and compensate circuit that we can try?

We cannot get the +/- 25 mV under 0-8A load transient testing yesterday.

thanks.

Prescott

0 JohnTucker over 9 years ago in reply to Prescott Siao

TI__Guru**** 191445 points

I do not directly support TPS54821 although, I know that part quite well. I am currently working on a time critical project, so I cannot spend design time on TPS54821. Let me see if I can find someone to help you in the mean time.

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TPS54821 Output Ripple