Introduction to 2n3773

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Introduction to 2n3773

• 2n3773 is an NPN power base bipolar transistor which is mainly designed for disk head positioners, high power audio, and other linear applications.
• Power switching circuits such as relays, DC-DC converters, and solenoid drivers also use this power transistor because it exhibits high switching performance.
• 2n3773 mainly consists of three terminals named as an emitter, base, and collector.
• It is completely characterized for linear operation and features high DC current gain and low saturation voltage.

• It is a current controlled device where small current at the base side is used to control large current at the emitter and collector side.
• When a voltage is applied at the base side, it gets biased and emitter emits the electrons which are then collected by the collectors.
• The base is used to control the number of electrons.
• Free movement of electrons between the terminals acts like a bridge that connects two terminals.
• Base side is lightly doped while emitter side is heavily doped in this transistor.

2n3773 Pinout

• A small current at the base side is used to control the large current at the base side.
• The ability of the base to control the number of electrons is used for amplification purpose.

Circuit Diagram of 2n3773

• This NPN transistor is a bipolar current controlled device which is different than JFET which is a unipolar voltage controlled device.
• Collector voltage is more than the base voltage and the base is positive with respect to the emitter.
• Emitter current is equal to the sum of base and collector current.
• This NPN transistor can be used with three configurations i.e common emitter configuration, common base configuration, and common collector configuration.
• Common emitter configuration is mainly used for amplification purpose because it features the required voltage and power gain for amplification process.
• Collector and emitter terminals exhibit different size and doping concentration. An emitter is highly doped while the collector is lightly doped.
• Forward current gain is an important factor in determining the characteristics of the transistor. It is an amplification factor i.e measure of current being amplified. It is called Beta, denoted by ß and is a ratio between collector current and base current. Beta value ranges between 20 to 1000 but its standard value is 200. As it is a ratio between two currents so it has no unit.
• Current gain is another important factor, known as alpha, denoted by a and is a ratio between collector current and emitter current. Alpha value ranges between 0.95 to 0.99. Most of the time its values is considered as unity.

Absolute Maximum Ratings

• Collector-Emitter sustaining voltage with an open base is 140 V.
• Collector-Base voltage with open emitter is 160 V.
• Maximum power it can dissipate is 150 W.
• These are the stress ratings, which if exceeded above absolute maximum ratings, can damage the device.
• Similarly, if stresses are applied for the extended period of time, they can affect the device reliability.

Difference between NPN and PNP Transistors

• There is a difference between NPN and PNP transistors based on charge carriers.
• Electrons are main charge carriers in NPN transistors while holes are main charge carriers in PNP transistors.
• Most of the experts prefer NPN transistors over PNP transistors because they think conduction carried out through electrons is better than conduction through holes.

Applications

• Disk Head Positioners.
• High power audio and Linear Applications.
• High-performance switching and amplification purpose.