BC557 SOT 23 PDF


Product data sheet. Supersedes data of Apr Oct DISCRETE SEMICONDUCTORS. BC; BC PNP general purpose. PNP general-purpose transistors in a small SOT23 (TOAB) Surface-Mounted Device. (SMD) plastic package. Table 1. Product overview. Low noise input stages of audio frequency equipment. DESCRIPTION. PNP transistor in a SOT23 plastic package. NPN complements: BC

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Similar Threads low-noise sot BJT transistors. There is one place for those fast transistor, st by GHz damping circuits close to the transistor: These have been addressed in various more advanced models: Most of the current is carried by electrons moving from emitter to collector as minority carriers in the P-type base region.

BJTs can be thought of as voltage-controlled current sourcesbut are more simply characterized as current-controlled current sources, or current amplifiers, due to the low impedance at the base. These electrons diffuse through the base from the region of high concentration near the emitter toward the region of low concentration near the collector. A bipolar junction transistor bipolar transistor or BJT is a type of transistor that uses both electron and hole charge carriers.

In a PNP transistor, the emitter—base region is forward biased, so holes are injected st the base as minority carriers.

BC – SMD – PNP General Purpose Transistor buy online at Low Price in India –

The base is very thin, and most of the holes cross the reverse-biased base—collector junction to the collector. In particular, the thickness of the base must be much less than the diffusion length of the electrons.

Detailed transistor models of transistor action, such as the Gummel—Poon modelaccount for the distribution of this charge explicitly to explain transistor behaviour more exactly.


As shown, the h-parameters have lower-case subscripts and hence signify AC conditions or analyses. Both types of BJT function by letting a small current input to the base control an amplified output from bbc557 collector. An increase in the collector—base voltage, for example, causes a greater reverse bias across the collector—base junction, increasing bc5557 collector—base depletion region width, and decreasing the width of the base.

Heterojunction transistors have different semiconductors for the elements of the transistor. Common source Common drain Common gate.

The diagram shows a schematic representation of an NPN transistor connected to two voltage sources. NPN is one of the two types of bipolar transistors, consisting of a layer of P- doped semiconductor the “base” between 32 N-doped layers.

This applied voltage causes the lower Sor junction to ‘turn on’, allowing a flow of electrons from the emitter into the base.

I’m working on two tables, a short one for inclusion sof the body of the transistor chapter, and a long one to be placed at the back of the book. The result is that the transistor makes a good switch that is controlled by its base input. The reason the emitter is heavily doped is to increase the emitter injection efficiency: By design, most of the BJT collector current is due to the flow of charge carriers electrons or holes injected from a high-concentration emitter into the base where they are minority carriers that diffuse toward the collector, and nc557 BJTs are classified as minority-carrier devices.

Hashed regions are depleted regions. It is common in modern ultrafast circuits, mostly RF systems. A Baker clamp can prevent the transistor from heavily saturating, which reduces the amount of charge stored in the base and thus improves switching time. The electrons in the base are called minority carriers because the base is doped p-type, which makes holes the majority carrier in the base.


The collector—base junction is reverse-biased, and so little electron injection occurs from the collector to the base, but electrons that diffuse through the base towards the collector are swept into the collector by the electric field in the depletion region of the collector—base junction.

The collector—emitter current can be viewed as being controlled by the base—emitter current current controlor by the base—emitter voltage voltage control. This page was last edited on 31 Decemberat In the discussion below, focus is 223 the NPN bipolar transistor. The h-parameter model as shown is suited to low-frequency, small-signal analysis.

This is called conventional current.

By convention, the direction of current on diagrams is shown as the direction that a positive charge would move. In the active mode of operation, electrons are injected from the forward biased n-type emitter region into the p-type base where they diffuse as minority carriers to the reverse-biased n-type collector and are swept away by the electric field in the reverse-biased collector—base junction.

This section may be too technical for most readers to understand. The remainder of the electrons recombine with holes, the majority carriers in the base, making a current through the base connection to form the base current, I B.

Sedra and Kenneth C.

Favorite BJT transistors, sot and TO equivalents – I | Electronics Forums

A small current leaving the base is amplified in the collector output. The bc575 main BJT amplifier topologies are:. Capital letters used in the subscript indicate that h FE refers to a direct current circuit. Your favorite candidates are solicited.