Obviously, as long as there is a input frequency that is 5mV RMS the IC can convert to a DC voltage value. But is there a minimum frequency where this IC would limit out on. I didn't see that in the datasheet.

It does DC, see the list on the first page "True RMS AC + DC Measurements". At low frequencies the chip will produce an output. The lower frequency limit is set by the *error in the RMS measurement*, which is more to do with being able to interpret the output as RMS. RMS is defined as an averaging integral. The averaging time is set by the averaging filter cap.

There is a point where you have to change your interpretation of the input signal being:

- a slowly changing "DC" input where the chip tracks the DC level, and

- an AC signal where you can compute the rms, which just happens to have a DC offset.

The averaging time sets the time scale where you interpret it one way or the other. There is a fuzzy zone where it is unclear which case it is and this is where the idea of measurement error at low frequencies creeps in.