Non-linear optocouplers are mainly used for the transmission of switching signals (or digital signals). The commonly used 4N series are 4N25, 4N26 and TIL117; there are also high-speed optocouplers, such as 6N136, 6N137, PS9714, PS9715, etc. It is mostly used for communication isolation and PWM wave control (which can effectively reduce electromagnetic interference). To determine whether it is a high-speed optocoupler, see whether the data sheet indicates High speed (1Mbps, 10Mbps).
Key Points:
● The core application of optocoupler is isolation;
● When the input resistance of the linear optocoupler is the same as the output resistance under the same voltage, the output current IC is basically the same as the input current IF; even if the input and output voltages are different, the resistance of the output and input can be matched to achieve;
● Both linear optocouplers and nonlinear optocouplers can be used for switching signals. Conversely, nonlinear optocouplers cannot be used in linear optocoupler circuits.
● The response speed of nonlinear optocoupler is faster than that of linear optocoupler, which is similar to the response speed of comparator faster than that of operational amplifier.