4N45-500E [Broadcom]

The 4N45/46 optocouplers contain a GaAsP light emitting diode optically coupled to a high gain photodetector IC. The excellent performance over temperature results from the inclusion of an integrated emitter-base bypass resistor which shunts photodiode and first stage leakage currents as well as bleeding off excess base drive to ground. External access to the second stage base provides the capability for better noise rejection than a conventional photodarlington detector. An external resistor or capacitor at the base can be added to make a gain-bandwidth or input current threshold adjustment. The base lead can also be used for feedback. The high current transfer ratio at very low input currents permits circuit designs in which adequate margin can be allowed for the effects of optical coupling variations. The 4N46 has a 350% minimum CTR at an input current of only 0.5 mA making it ideal for use in low input current applications such as MOS, CMOS and low power logic interfacing. Compatibility with high voltage CMOS logic systems is assured by the 20V minimum breakdown voltage of the output transistor and by the guaranteed maximum output leakage (I_OH) at 18V. The 4N45 has a 250% minimum CTR at 1.0 mA input current and a 7 V minimum breakdown voltage rating.