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Why is a transistor used as a switch in place of a regular mechanical switch?
When using the transistor as a switch, a small Base current controls a much larger Collector load current. When using transistors to switch inductive loads such as relays and solenoids, a “Flywheel Diode” is used. When large currents or voltages need to be controlled, Darlington Transistors can be used.
What is load on switch?
1 What Are Load Switches? Integrated load switches are integrated electronic switches used to turn on and turn off power rails. When the device is enabled via the ON pin, the pass FET turns on, thereby allowing current to flow from the input pin to the output pin, and power is passed to the downstream circuitry.
What happens when you use a transistor as a switch?
Transistors that are fully “ON” are said to be in their Saturation region. Transistors that are fully “OFF” are said to be in their Cut-off region. When using the transistor as a switch, a small Base current controls a much larger Collector load current.
Which is the controlling switch in a NPN transistor?
Consider an NPN transistor as shown in Figure. Z is the load in the collector circuit and the controlling switch S is in the base circuit. When switch S is closed, the base-emitter junction is forward biased and the transistor conducts i.e. current starts flowing through load Z.
Why are multiple transistors used in a bipolar transistor?
Sometimes the DC current gain of the bipolar transistor is too low to directly switch the load current or voltage, so multiple switching transistors are used. Here, one small input transistor is used to switch “ON” or “OFF” a much larger current handling output transistor.
How does a Darlington transistor work as a switch?
Darlington Transistors simply contain two individual bipolar NPN or PNP type transistors connected together so that the current gain of the first transistor is multiplied with that of the current gain of the second transistor to produce a device which acts like a single transistor with a very high current gain for a much smaller Base current.