Optoelectronics

Notes

1. An open collector (OC) output can sink current but cannot source current; it must be used with a pullup resistor.  The amount of current that it can source is approximately Vsource/(Rpullup + Rload) since the voltage drop introduced by the device is only about 200mV if a BJT or adds only about 100ohms of resistance if a FET, when fully turned on.