LMR36503: I have some confuse about auto mode and fpwm mode

Part Number: LMR36503

our product use your fix 3.3v of parts

but i have some confused about this statement

in fpwm mode , there first paragraph tell us ''In FPWM Mode, frequency is maintained while lightly loaded.'', means that in fpwm mode, the frequency is a fix frequency, but the second paragraph say in fpwm mode the frequency reduction is still available if output voltage is high enough to command minimum on-time even while lightly loaded, i want to know what's ''output voltage is high enough to command minimum on-time'', this high voltage value is how much ?

looking forward to your reply, thanks!