Mmm, just read some documentation about this. There's some sort of switching transistor inside those AMC7135's, that is the switch you mean, I guess.
“… high enough” for you, of course. Everyone's sensitivity is/may be different. However, “PWM” here means that, in essence, light output isn't “continuous”, but a sequence of PWM wave periods.
Honestly, PWM is suited for strobe and SOS, which are periodic signals. However, “emulating” a continuous “stream” of light through a periodic PWM on/off wave is, or can be, extraordinarily gross. The lower the PWM frequency (flicker) and magnitude (efficiency), the grosser. 1% PWM moonlight mode? :facepalm: LoL! The amount of drawbacks I can see on this now, in practice (efficiency, flicker, etc), is quite substantial.
I'll be back.
Cheers ^:)