Power Transistor
In this topic,the symbol of PNP and NPN transistor are shown in terms of diode comparison.As common emitter configuration is mostly used for amplification and switching application, the circuit diagram, input characteristics and output characteristics of it is discussed. And finally, it is closed with basic application of transistor.
Summary
In this topic,the symbol of PNP and NPN transistor are shown in terms of diode comparison.As common emitter configuration is mostly used for amplification and switching application, the circuit diagram, input characteristics and output characteristics of it is discussed. And finally, it is closed with basic application of transistor.
Things to Remember
1)Power Transistor is a three-terminal device in which a layer of n-type semiconductor is sandwiched between two layers of p-type semiconductor(or a layer of p-type semiconductor is sandwiched between two layers of n-type semiconductor).
2)It posses a controlled characteristics.
3)Cut off region, Saturation region and active region are the three regions present in the output characteristics of transistor in common emitter configuration.
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Power Transistor
Power Transistor
Power Transistor is a three-terminal device in which a layer of n-type semiconductor is sandwiched between two layers of p-type semiconductor(or a layer of p-type semiconductor is sandwiched between two layers of n-type semiconductor). It posses a controlled characteristics. When a current signal is provided to the base of the power transistor, it turns on and it remains in on the state as long as the current signal is provided to it.
V-I Characteristics
Common Emitter Configuration is widely used for the purpose of switching in the NPN power transistor.
A graph between base current Ib and base-emitter voltage gives the input characteristics. The graph below resembles the V-I curve for forward biased operation of the diode as the base-emitter junction of a transistor is like a diode. When the Vce is increased, for the same Base-Emitter voltage, a smaller value of Base Current is required.
Output characteristics are the curve drawn between Vce and Ic. For the output characteristics,there are three operating regions of a transistor.
a)Cut off region
b) Active Region
c) Saturation Region
In the cutoff region, the base current isn’t enough to turn the transistor on and both junctions are reversed biased, therefore, the transistor is in off state.
In the active region,the transistor acts as an amplifier, where the collector current is amplified by a gain and for the same value of collector current, Vce decreases as the value of base current is increased. The collector-base junction is reverse biased and the base-emitter junction is forward biased.
In the saturation region, the base current is sufficiently high so that the collector-emitter voltage is low and the transistor acts as a switch. Both junctions are forward biased.
Application of Transistor
- As a switch
- As an Amplifier.
Lesson
Characteristics and Specification of Power Electronics Devices
Subject
Electrical Engineering
Grade
Engineering
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