What I was told is that the lowest frequency is equal to the wattage, not sure about the highest but I think that depends on the source.
You can set the software for whatever you like the min/max to be, but the source will default to the actual min/max. My 30 watt machine had a min value of 20 and a max value of 80 in the configuration, not sure what the actual max is but the actual min is 30 and I changed the software to reflect that value.