UCC28180: UCC28019A Comparison

Part Number:UCC28180

Hello,

I'm designing a PFC boost controller off a universal AC input. It looks like the UCC28180 and UCC28019A are very similar. The main noticeable difference I saw is that the UCC28019A senses the AC input voltage while the UCC28180 allows for variable switching frequency.

Are there any noticeable differences between the two? Is the AC line sensing used for anything other than brown-out detection? Any other considerations that would suggest using one part over the other?

Thanks!