Now the question is how can we use PNP transistor as a switch?As we have seen in the working of the PNP transistor, if the Base voltage is not more negative then Emitter voltage, the current cannot flow through the device. The small amount of base current controls the flow of a large amount of current through emitter to collector provided that the Base voltage is more negative than the Emitter voltage.If the Base voltage is not more negative than the Emitter voltage, the current cannot flow through the device. Therefore, a very large number of holes from emitter cross the depletion region and enter the Base. Electrons travel slowly in a semiconductor and holes move more slowly than electrons. Click here to see our privacy policy.
While the Collector-Base junction is in reverse bias and hence the depletion region at Collector-Base junction is wide.The Emitter-base junction is in forward bias. P type semiconductor contains holes and This holes going to transfer to the base. Regarding the three terminals of the PNP transistor, the Emitter is a region is used to supply charge carriers to the Collector via the Base region. PNP Transistor: How Does it… Working Principle of Transistor; Current Components in a Transistor; Transistor as an Amplifier; Please feel free to contact us if you’d like to request a specific topic. Pnp transistor working – In the above figure shows the basic connection of pnp transistor. The arrowhead shows that the current will flow through Emitter to Collector.Due to this type of bias, the depletion region at Emitter-Base junction is narrow, because it is connected in forward bias. PNP Transistor is a sub-type of Bipolar Junction Transistors (BJT’s). The forward bias between emitter and base cause current to flow from p type emitter to n type base.
To understand the working of a Transistor, it is necessary to know the characteristics of semiconductors. In PNP transistor circuit, the base is always negatively biased with respect to the emitter and this type of switching is used for negative ground configuration.
But The number of electrons in the Base is very small because it is a very lightly doped and thin region. It means that, if the Base voltage is zero or less than 0.7 V, the current cannot flow and it acts as an open circuit.
The Base region triggers and controls the amount of current flows through the Emitter to Collector.The construction of a PNP transistor is very similar to the construction of The construction of the PNP Transistor is as shown in the below figure.The middle layer (N-type layer) is called the Base terminal (B). In this switching, base current flows when the base voltage is more negative.
Working of PNP Transistors: As discussed above, the transistor is a current controlled device which has two depletion layers with specific barrier potential required to diffuse the depletion layer. The current flow is due to the movement of holes. PNP transistor works when the emitter-base junction is forward biased while collector-base junction is reverse biased. She is an author, editor and partner at Electricalfundablog.PNP Transistor – Working Principle, Characteristics & ApplicationsInput Characteristics for Common-Base ConfigurationOutput Characteristics for Common-Base Configuration
Reverse biasing creates no diffusion and hence no current flows between the terminals.The Base Emitter region is forward biased so that the voltage at the Emitter is at higher potential than at the Base (VAt the same time, electrons flow from negative terminal pushing the electrons near the Emitter-Base junction into the Emitter. Working of NPN Transistor. In this bipolar junction transistor, the voltage across the emitter-base junction (that is in forward-bias) is always less than the collector-base junction (reversed-bias). Simultaneously, very few electrons enter in Emitter from the base and recombine with the holes.The loss of holes in the emitter is equal to the number of electrons present in the Base layer. When these electrons move into the N-type semiconductor material or base, they combined with the electrons. The structure is opposite to NPN transistor but similar in operation.The PNP Transistor symbol shows an arrow pointing inwards from Emitter to the Base which indicates the direction of the conventional current flow.