I got confused when I saw this on a HCPL-181 optocoupler datasheet.
You can get the datasheet here: HCPL-181 datasheet.
So what would happen if the collector current goes below 2.5mA? (In fact I am using the optocoupler for a 50uA output current.
Electronic – Why is there a minimum Ic for a optocoupler
opto-isolator
Related Solutions
Did you consider that the LED of the optocoupler limits the voltage at the output (pin1) to its forward voltage. I.e. the voltage divider that provides the reference voltage (at pin3) is always loaded not only by the bottom resistor (500 Ohm) but also by the branch via 300 Ohm resistor and LED.
Maybe this causes the threshold to be not where you think it is.
I recommend to connect the cathode of the LED to the ouput of the comparator (it's open drain anyway), connect the diode's anode via a restor to Vcc and reverse positive and negative inputs of the comparator.
simulate this circuit – Schematic created using CircuitLab
When V1 < 3.3V, Q1 OFF, V2 = 0
When V1 = 3.3V, Q1 ON, V2 = 5
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Best Answer
The stated Collector Current rating in the datasheet refers to minimum and maximum guaranteed current that the transistor collector will pass, for a current of 5 mA through the LED. The variation accounts for manufacturing differences between pieces, not for an individual part.
This does not prevent the application from passing less current by external limiting of the current.
The datasheet information, and the corresponding behavior, are similar to conventional BJTs, other than that the corresponding base current is not specified.