The functional difference between a PNP transistor and an NPN transistor is the proper biasing (polarity) of the junctions when operating.

The schematic symbols are shown in Figure below(a) and (d).īJT transistor: (a) PNP schematic symbol, (b) physical layout (c) NPN symbol, (d) layout. Each layer forming the transistor has a specific name, and each layer is provided with a wire contact for connection to a circuit. In taking this approach, however, I assume that the reader possesses a certain minimum knowledge of semiconductors: the difference between “P” and “N” doped semiconductors, the functional characteristics of a PN (diode) junction, and the meanings of the terms “reverse biased” and “forward biased.” If these concepts are unclear to you, it is best to refer to earlier chapters in this book before proceeding with this one.Ī bipolar transistor consists of a three-layer “sandwich” of doped (extrinsic) semiconductor materials, either P-N-P in Figure below(b) or N-P-N at (d). I don’t mean to downplay the importance of understanding semiconductor physics, but sometimes an intense focus on solid-state physics detracts from understanding these devices’ functions on a component level.

Here I want to explore how to use these components, not analyze their intimate internal details. Discussions of holes and electrons are better left to another chapter in my opinion. My intent here is to focus as exclusively as possible on the practical function and application of bipolar transistors, rather than to explore the quantum world of semiconductor theory. Understanding how transistors function is of paramount importance to anyone interested in understanding modern electronics. This revolution made possible the design and manufacture of lightweight, inexpensive electronic devices that we now take for granted. Technical feats previously requiring relatively large, mechanically fragile, power-hungry vacuum tubes were suddenly achievable with tiny, mechanically rugged, power-thrifty specks of crystalline silicon. The invention of the bipolar transistor in 1948 ushered in a revolution in electronics. Introduction to Bipolar Junction Transistors Collector Emitter Voltage V(br)ceo: 45V.BC 547 NPN transistor 45V 100mA hFE 150 Specifications:

Bc547 transistor download