Transistors are semiconductor devices with at least three outputs. In certain situations, they are able to amplify power, generate oscillations or convert a signal. There are many different designs of these devices, and among them is a pnp transistor.
Classify transistors by semiconductor material. They come in silicon, germanium, etc.
If a transistor has three regions, two of them have hole conduction, it is called "forward conducting transistor", or "pnp junction transistor". A device in which two regions are electronically conductive is called a reverse conducting transistor, or npn junction. Both transistors work in the same way, and the difference lies solely in polarity.
Where is the pnp transistor used?
Depending on what characteristics a transient has, it can be used for a variety of purposes. As already mentioned, the transistor is used to generate, convert and amplify electrical signals. Due to the fact that the input voltage or currentchange, the input circuit current is controlled. Small changes in the parameters at the input lead to an even greater change in the current and voltage at the output. This gain property is used in analog technology (radio, analog TV, communications, etc.).
In our time, a bipolar pnp transistor is used for analog technology. But another, very important industry - digital technology - has almost abandoned it and uses only field technology. The bipolar pnp transistor appeared much earlier than the field-effect transistor, therefore it is commonly called simply a transistor.
Performance and parameters of transistors
Transistors are structurally manufactured in plastic and metal cases. Given the different purposes of transistors, these devices are selected according to certain parameters. For example, if you need a transistor to amplify high frequencies, it must have a high signal amplification frequency. And if the pnp transistor is used in a current regulator, it must have a high collector operating current.
Reference literature contains the main characteristics of transistors:
- Ik - working (maximum allowable) collector current;
- h21e - gain factor;
- Fgr - maximum gain frequency;
- Pk is the collector power dissipation.
Phototransistors
A phototransistor is a device that is sensitive to the light flux that irradiates it. In a hermetically sealed case of such a transistora window is made, for example, from transparent plastic or glass. The radiation through it enters the zone of the base of the phototransistor. If the base is irradiated, then charge carriers are generated. The phototransistor will open when the charge carriers pass into the collector junction, and the more the base is illuminated, the more significant the collector current will become.
Modern electronics cannot be imagined without transistors. Almost no serious device can do without them. Through the years of application and improvement, transistors have changed significantly, but the principle of their operation remains the same.
