How to calculate LTC3780, LTC3789 Ith Pin filter?


Could someone be so kind as to explain how the RC filter is derived for the Ith Pin?  One example shows an 8k and 2200pF, and another example has a 15k and a 10nF.  Then a third example has a 68k and 3300pf.  The datasheet explains it is a current limit,  but if one uses the IO sense to set a current limit why is it also being connected?

I calculated the filter frequency and one is at 9khz, and then the 68k 3300pF is 700hz?  all the examples run at 400khz.