In case of output become shorted the input circuit will become open without affecting it. Whenever the data will start transfer there won’t be any communication between each circuit. The above circuit will be designed with an LED just to detect the signal transferring and the resistances will be used to limit the voltages. To design an isolation circuit of a 3 to 5-volt circuit we will use some resistances and other devices will be according to the optocoupler requirement. In Isolation, the circuit communicates between two devices without any delay and it protects the circuit with low voltage from the high voltages. The module is basically knowing as isolation module but due to its high speed, it is also known as HIGH-SPEED ISOLATION METHOD. In the example of 6N137 optocoupler, we will design a module that is used for isolation between two circuits. Here the graphical representation of propagation delay: Each output state will change after 50ns change in logic input no matter which input state optocoupler is receiving. This will only happen after 50ns change in logic state. In the above truth table as you see some LOW and HIGH states for output. In 6N137 the output could be affected by propagation delay easily which is 5ns. In high-speed devices the propagation delay should be understood properly otherwise it could affect the output very badly. The enable pin value and the input signals combination gives the output state which can be considered according to the following truth table: TRUTH TABLE Even when there is no connection it will affect the output due to its default state, but it can be changed by proving logical signals. The default state of enabling pin is HIGH. Here enables pin will be used to deliver the different outputs. There is another pin on the IC know as enable pin, are most of the cases the enable pin gives the power on and off the ability to control devices. The pull up resistor value will be different according to its requirement. The input signal of the in the IC can be probed but only when it necessary otherwise it won’t be necessary. The value of the pull-up resistor is 330 to 4k which van avoid the floating error when the load will be connected at the output. The transistor can absorb the current or it can store the current too but to avoid storage for further output error a pull-up resistor will be used to avoid it. The output pin of the IC contains an NMOS transistor which acts as a switch. It also should have an impedance of about 50ohm. Then the input single should have the 5ns rise and fall time to get the response from the IC. Due to its dual capability of using both current AC and DC current, it should be connected with 0.1uF bypass capacitor with the power supply to avoid decoupling between both ends. To use the optocoupler there is some requirement for every circuit. IR receiver output and enable pin both are connected to the NAND gate which helps to decide the output. The output is decided on the base of input and an enable pin. The optocoupler 6N137 is one of the high speeds optocouplers due to its fast IR transmitter and receiver. So, in those cases where high-speed optocoupler is needed the IC will be a perfect device to remove the noise and data conversion. Optocoupler can work with both AC and DC but using it with any circuit a 0.1uF capacitor is recommended. It also comes up with an enable pin which makes it handy for using in-circuit of flash for the camera. The recommended operating voltage for IC is 5V but at the output side, it does not support the switching of high load which makes it suitable only for LOW voltage devices. IC 6N137 internally comes up IR transmitter but the receiver end comes up with an NMOS transistor which keeps it protected from leakage. This optocoupler comes up with 10Mbit/sec speed which uses as optocoupler between two circuits for multiple purposes. An optocoupler name 6N137 is designed as one of the high-speed optocouplers. Every optocoupler comes with a different feature to solve the requirement in every situation. 6N137 is a single-channel high-speed optoisolator.
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