Basically, low speed awareness tapes are just alpha information superimposed on speed tape. If you are trying to fly 110 ton jet with 100t approach speed, you'll need higher AoA to fly it down the glide, that's how ADC knows you are flying closer to stall.
The AoA measures how close we are to the critical AoA. In level flight, that AoA will be reached at different speeds depending on weight.
Given that the critical AoA remains constant, how does the computer know that we will stall at a higher speed? In my airplane, the FMS doesn't send any sort of W&B info to the ADC's. So how does the computer know where to place the stall speed at different weights?