Drive the output LED in parallel with R8, it could be operated with only 1 mA or so as modern LEDs can be bright with only a small current. 4N25: 878Kb / 13P: 6 PIN DIP PHOTOTRANSISTOR Fairchild Semiconductor: 4N25: 210Kb. 4N25: 101Kb / 1P: Optically-Coupled Isolator Optoelectronic Products Fairchild Semiconductor: 4N25: 608Kb / 15P: GENERAL PURPOSE 6-PIN PHOTOTRANSISTOR OPTOCOUPLERS Everlight Electronics C. Isolation Test Voltage 5300 Vrms Interfaces with Common Logic Families Input-Output Coupling Capacitance<0.5pF Industry Standard Dual-in-Line 6-Pin Package.
4N25 OPTICAL ISOLATOR SERIES
You could also do something like using two couplers with the LEDs in series driven by about 40 mA, but put their outputs in parallel. 4N25: 610Kb / 5P: GAAS INFRARED EMITTING DIODE New Jersey Semi-Conduct. Optocoupler, Phototransistor Output, with Base Connection (AA Enabled) 4N25. Again if you put a transistor after the photo-coupler to amplify the current it should be no problem to meet your requirements. Browse Cadence PSpice Model Library 4N24.
4N25 OPTICAL ISOLATOR PLUS
This will prevent the output (Out) going below about 2 V (LED voltage plus the voltage across the photo-coupler). The LM339 is only guaranteed to be able to sink 6 mA (typically 16 mA), so it will have difficult time directly driving the 4N25 with a high current.Ģ: You have the output LED on the ground side of the photo-coupler. 1 2 nc3 4 6 Vcc R L Figure 4.34: 4N25 optical isolator (4.5.1 SONALERTS, BEEPERS, AND BUZZERS In Figure 4.35, we show several circuits used. You may be able to inject enough to get the output current you require, but it would probably be better to put amplification after the optocoupler. Optoisolator Transistor with Base Output 2500Vrms 1 Channel 6-DIP. Each optocoupler consists of gallium arsenide infrared LED and a silicon NPN phototransistor. 4N25 is also a widely used optocoupler / optoisolator / photocoupler, It is a general purpose optocoupler like PC817, MOC3021 etc. You have less than 2 mA being put into the LED, but require about 10 mA from the 4N25 phototransistor.Īlso from the data sheet the absolute maximum current you are permitted to inject into the LED is 60 mA. 4N25 Description The 4N25 series is industry standard single channel phototransistor coupler. An opto-isolator is an electronic component that transfers electrical signals between two isolated circuits by using light. This means that the current out of the photo-transistor may be as little as 1/5 of the current the is injected into the LED. 1: A 4N25 only has what is called a Current Transfer Ratio of as low as 20% ( 4N25 datasheet).