I have a question regarding the MOC30XX series opto-couplers. What is the real difference in their operation? So far I know only that the forward current of the input driving diode is 15, 10 and 5 mA respectively. Is there any difference in their theory of operation, ie. auto turn-off at 0 cross etc? I would appreciate all info.
These all have triac outputs. Triacs have the intrinsic feature to turn off at currents below the holding current. The control circuit takes care not to turn on immediately when the voltage isn't near zero. That makes it safe to use that part as a on/off switch in a simplyfied circuit for inductive and capacitive load. You cannot control phase-angle that way, though.
The MOC3041/42/43 are binned for manufacturing tolerances of the optocouple. That's it.