UCC28070: PF Not improving

Hi Aswathy, an expert will get back to you tomorrow, thanks.—— Teng

Hi Aswathy,

thanks for your interest at  UCC28070, usually the reason UCC28070 can not achieve a good PF at full load is you still do not improve the the external circuit parameter values or you have a bad layout that cause noise.

my suggestions are:

1.use TI's UCC28070 excel tool to evaluate whether your schematic is correct,

2. check your layout to see whethe vinac, vsense have a clean samling signal.

Below is the excel tool link:

http://www.ti.com/product/UCC28070/toolssoftware

Hi,

Thanks for the response. Please see attached input current & voltage waveform of my PFC. As you can see, there is a current spike in every cycle. What might be the reason for it?

Thanks & Regards,

Aswathy

Hi Aswathy,

sorry for the delay response. May I know whether you have any progress on this issue?

Your input current waveform is strange to me.

can you send the schematic to me?

also can you scope the Vinac PIN signal and Vimo pin at the moment you see the current spike to me?

thanks.

Hi,

The issue is not resolved yet. PFA-Schematics. The output of PFC is connected to 7.32mF cap. W/F is for 4.4kW load @ 230Vac. PFC voltage is 400V. Expecting your response on this soon..

Hi Aswathy:

the schematic you attached is not clear enough for me to check the value. Can you send it directly to me through wenbin-huang@ti.com?

please also scope the waveform I need in the previous post?

in order to know about the system, please help fill in below information:

thanks.