Hi, my name is Oliver Kim, TI Field application Engineer.
When I studied the PFC Controller, most of the applications selected the boost PFC controller such as UCC28019 typical application diagram.
Could you let me know why we can usually use boost PFC, not the BUCK?
Of course, I know in case of step down voltage application, buck PFC controller is also needed.
But it seems that most of the documents and articles say about boost PFC controller basically.
For example, On-board charger always uses boost PFC. But I think Buck PFC also can be used because there is a Full bridge DC-DC converter so we can control again the voltage level by the ratio of the coils.
Someone tells that it's a kind of energy storage efficiency reason: high voltage with low current is better than high current with low voltage, so we use boost PFC!
..Well, why high voltage is better??
This doesn't clearly solve my curiosity. Is there any other reason?
I really need your help.
Thank you.