UCC28070-Q1: input current unstable while input voltage is higher than 250Vac

shuang qiu

Part Number: UCC28070-Q1
Other Parts Discussed in Thread: UCC28070

Hi,

We used UCC28070 on traditional boost PFC. It's found that the input current became unstable while the input voltage is higher than 250Vac. That is not related to loading as we changed loading from light load to full load, it is there always. attached waveform channel1 is input voltage, channel2 is input current. Please advise. Thanks.

over 6 years ago

0 John Griffin1 over 6 years ago

TI__Mastermind 34465 points

Hello shuang qiu,
You will need to start by reviewing your schematic and design requirements.
Are these documents available ?
Did you run the Excel calculator tool to calculate the correct component values ?
It may be that the boost inductance value is too low or the Rsynth value is not calculated correctly.
Without the design requirements and an accurate schematic it is not possible to give any more sugeestions.

Regards
John

0 shuang qiu over 6 years ago in reply to John Griffin1

Prodigy 190 points

Hi John,

We used Excel calculator tool to select correct value already. No saturation found.
It seems when input voltage peak value is closed to output voltage, about 10~20V deviation, the input current became unstable, no matter load current.

0 John Griffin1 over 6 years ago in reply to shuang qiu

TI__Mastermind 34465 points

Hello shuang qiu,
Let me know if you need further help or suggestions.
Good Luck
John

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UCC28070-Q1: input current unstable while input voltage is higher than 250Vac