There is a lot of misunderstanding here so far. I'll try to clear it up for you.
1. A-floor is an ATHR function, not F/CTL, as has been correctly stated.
2. It will activate whether or not the ATHR is active.
3. It activates at the A-floor threshold which is dependant on the aircraft configuration (Flap 0, 1, 2, 3 or FULL).
4. The A-floor threshold is an angle of attack. Without looking it up I think it is 9.5 deg AoA in flap 0 and 13-15 deg AoA in other configs. The precise threshold depends on the 320 variant.
5. A-floor reverts to TOGA LK when the aircraft AoA returns to a value below the A floor threshold. This is at no precise point on the speed scale which can be identified by the pilot.
6. Any sharp pitch up input can provoke A-floor at speeds well above VLS/A Prot because there will have been an instantaneous increase of the AoA above the A-floor threshold.
HTH,
WS