I am interested in using this opto-coupler in my design in which I need the opto-coupler NOT to turn on below 2mA. Based on the Si87xx datasheet on page 4, the Si87xxA has input curent min at 3mA and Max at 15mA. It also has input current threshold IF(TH) at 1.8mA max. Does this mean the LED of the opto will turn on at 1.8mA or at lower current than that? Or does it turn on even at lower than 1.8mA?
Appreciate your help on this.
The 3mA to 15mA spec is the recommended operating condition. The Si87xxA and Si87xxC devices are guaranteed to be ON if you apply at least 1.8mA of current to the input. It is possible they could turn on at a lower input current.
I hope that is helpful,