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Why optocoupler is used in relay?
The well-established relay-driving circuit uses an optocoupler to isolate the grounds and noise coupling between the low-voltage digital-control signal circuit (left) and the relay as load (right). This, in turn, energizes the relay.
Why we use mosfet as a switch?
When using the MOSFET as a switch we can drive the MOSFET to turn “ON” faster or slower, or pass high or low currents. This ability to turn the power MOSFET “ON” and “OFF” allows the device to be used as a very efficient switch with switching speeds much faster than standard bipolar junction transistors.
What is special about MOSFET?
The MOSFET or metal oxide semiconductor field effect transistor, is a form of FET that offers an exceedingly high input impedance. The gate input has an oxide layer insulating it from the channel and as a result its input resistance is very many MΩ.
How many types of Mosfet are there?
There are two classes of MOSFETs. There is depletion mode and there is enhancement mode. Each class is available as n- or a p-channel, giving a total of four types of MOSFETs.
Can a microcontroller drive a MOSFET with an optocoupler?
Anything up to about 10 kHz should work OK./ For faster PWM a properly designed driver is required. As far as the MOSFET is concerned, an optocoupler is just a transistor. As far as the microcontroller is concerned, an optocoupler is just an LED.
How does an optocoupler limit the gate voltage?
You can limit the gate voltage by having a resistor in series with the optocoupler’s transistor. If the transistor to ground is 4k7 you can pick 10k for this. If the optocoupler’s LED is on the transistor will conduct and make the gate high, switching the MOSFET on.
How are optocouplers used in an electrical system?
Optocouplers also make it convenient to control the connection between two circuits by connecting and disconnecting them via an optocoupler. Optocouplers are extensively used in electronics, electrical, and communications systems. Optocouplers are often used to reject back EMF, noise, and electrical surges from entering an MCU circuit.
Why are optocouplers more sophisticated than fuses and fuses?
Optocouplers can avoid a great deal of cost in replacing components by protecting them. However, optocouplers are more sophisticated than fuses. Optocouplers also make it convenient to control the connection between two circuits by connecting and disconnecting them via an optocoupler.