What optocoupler has the lowest led diode input current
that brings the output transistor to saturation?
CNY17 has 10mA.
I am connecting the input to 220V 50Hz so I need
low input led current to save watts of the input
resistor.
This partly depends on what the load will be. What are you connecting
to the output?
There are many opto's out there, but i think 1ma might be a good lower
limit to count on, provided you can rig the output to only draw 1ma too.
I guess you only need 50Hz frequency response then too?