2N2219 Transistor : Pin Configuration, Working & Its Applications

The 2N2219 transistor is similar to the 2N2222 NPN transistor. However, it is housed in a metal case and can operate at slightly higher voltages than the 2N2222. These are usually just low-power signal transistors, commonly used in amplifier and switching circuits. So, for a better load-switching NPN transistor, the 2N2219 might be a good choice for the project.

The equivalent and alternative 2N2219 transistors are BC636, BC639, BC547, BC549, 2N2369, 2N3906, 2N3904, 2SC5200, 2N5551, and 2N2905 (2N2219 PNP transistor). This article gives a brief description of pin configuration, specifications, circuit diagram, and applications of a 2N2219 transistor.

What is a 2N2219 Transistor?

2n2219 is an NPN bipolar transistor, which is commonly used for small signal amplification and switching applications. It consists of 3 terminals: Emitter, Base, and Collector. The base terminal is positive with respect to the collector terminal. Although the conduction is carried out by the charge carriers (electrons and holes), it is called a bipolar transistor, but most of the electrons are the charge carriers.

2N2219 Transistor
2N2219 Transistor

The electron’s movement plays a vital role in determining the conductance of this 2N2219 NPN transistor. The 2N2219 NPN transistors are configured into 3 different transistor configurations as Common Emitter, Common Base, and Common Collector.

The 2N2219 transistor is a current-controlled device that uses low current at the base terminal to control high current at the emitter and collector terminals. When a positive voltage is fed to the base terminal, electrons begin to flow from the emitter to the collector, and the number of electrons is controlled by the base.

Because the 2N2219 is an NPN transistor, the collector and emitter remain open (reverse bias condition) when the base terminal is held to the ground and remain closed (forward bias condition) when the input signal is applied to the base terminal. 2N2219 has a gain of 50hfe, which determines the amplifying capacity (gain) of the transistor. The maximum current of 800 mA flows through the collector terminal, so this transistor should not be connected to a load that draws more than 800 mA.


2N2219 Transistor Biasing

For biasing the transistor, it is necessary to apply current to the base terminal. This current (IB) value must be limited to 5mA by connecting the transistor to the base terminal. When the 2N2219 transistor is in fully biased condition, up to 800 mA of maximum current can flow through the collector and emitter terminals. This phase is called the saturation region. If the base current is removed, then the transistor goes to OFF condition completely, and this phase is called the cut-off region, and the base-emitter voltage can be about 600 mV.

The silicon 2N2219 NPN transistor features a base with a positive and an emitter with a negative. Similarly, the voltage on the collector terminal is greater than the voltage on the base terminal. These transistors can be configured in three basic configurations.

The common emitter configuration is mainly used for amplification purposes because it includes the appropriate voltage and power gains needed for amplification purposes. In this configuration, the input signal can increase by 20 dB, which is 100 times greater than the input signal. The collector and emitter differ slightly in size and doping concentration.

The emitter is a highly doped alloy and the collector is lightly doped This NPN transistor is a bipolar control-current device, and unlike MOSFETs, it is a unipolar control-current device. Current gain is an important property that is mainly used to determine the gain of a transistor.

Current Gain of 2N2219 Transistor

The forward current gain is usually referred to as the beta version, denoted by β (beta), which is the ratio of the collector current to the base current. This is called the factor of amplification and it is a measured amplified current. Beta values range from 20 to 1000, but the default is 200. Beta is the ratio of the two current values, so it has no units.

The current gain of the 2N2219 NPN transistor is expressed as ‘α’ (alpha), the ratio of the collector and emitter currents, ranges from 0.95 to 0.99, with a value of 1 being considered in most cases. NPN and PNP transistors differ in their charge carriers. Electrons are the major charge carriers of NPN transistors and holes are the major charge carriers of PNP transistors.

The open-emitter with collector-base voltage is 60V and the open-base with collector-emitter voltage is 30V. The maximum power dissipation is 800 mW. This is an approximate voltage and the device may be damaged if the voltage exceeds the absolute maximum. Similarly, the applied voltage over a long time can affect the reliability of the device.

2N2219 Transistor Pin Configuration/Pin Diagram:

The 2N2219 NPN transistor consists of three terminals/leads/pins that determine its nature. When a little voltage is fed to the base terminal, then, it is biased allowing a small current on the base terminal to drive a large current on the emitter and collector side. Conductivity is achieved by transferring electrons from the emitter to the collector, and the base is used to control the number of electrons. The 2N2219 transistor pin configuration/pin diagram is illustrated below.

2N2219 Transistor Pin Configuration
2N2219 Transistor Pin Configuration
  • Pin 1 (EMITTER): This pin refers to the current flowing through an emitter connected to the ground.
  • Pin 2 (BASE): This pin refers to controlling the biasing conditions of the transistor. And also used to turn the transistor ON and OFF.
  • Pin 3 (COLLECTOR): This refers to the current that usually flows through a collector connected to the load.

Technical Specifications:

The features and technical specifications of the 2N2219 transistor are given below.

Absolute Characteristics:

  • The 2N2219 is a small signal general amplification purpose NPN bipolar transistor available in the To-92 package.
  • Collector-to-Emitter voltage (VCE) is 50V(dc).
  • Collector-to-Base voltage VCB is 75V(dc).
  • Emitter-to-Base Voltage VEB is 6.0V(dc).
  • Continuous collector current IC is 800mA(dc).
  • Total power dissipation @ 25°C is 0.8-3.0W.
  • The storage and operating temperature range is -65°C to +200°C.
  • Thermal resistance (junction to case) is 50°C/W.

Electrical Characteristics: (@T=25°C):

  • Collector-to-Emitter Breakdown voltage is 30Vdc-50Vdc
  • Emitter-to-Base cutoff current is 10microAmps (dc).
  • Collector-to-Emitter cutoff current is 20microAmps(dc).
  • Collector-to-Base cutoff current is 10microAmps(dc).
  • DC’s current gain hFE is 35.
  • Collector-to-Emitter saturation voltage VCE(sat) is 0.4V(dc).
  • Base-to-Emitter saturation Voltage VBE(sat) is 1.3Vdc.

Small-Signal and switching Characteristics:

  • Small-signal current gain magnitude |hfe| ranges from 2.5-12.
  • Small signal current gain hfe is 50.
  • Input capacitance is 25pF.
  • Output capacitance is 8.0pF.
  • Turn-OFF time is 250ns.
  • Turn-ON time is 40ns.

Circuit Diagram of 2N2219 Transistor/How to Use:

The 2N2219 is an NPN BJT transistor, commonly used for small signal general purpose and switch in many circuit applications. So let’s know how to use it in the example circuit. Since the transistor is an NPN type, the switched load must be connected to the collector and the emitter to the ground, as shown in the circuit diagram.

Circuit Diagram of 2N2219 Transistor
Circuit Diagram of 2N2219 Transistor

Another important point to be considered is the base resistor when using a transistor as a switch. The current flowing through the base is limited by connecting this resistor to the base terminal of the transistor. Since the transistor is a current-controlled device (turn ON), we need to allow some current (IB) through the base of the transistor to power the transistor. This current value can be calculated based on the amount of current required by the load.

Here we can assume that the load draws a maximum of about 800mA, so the collector current (IC) is 800mA. To allow this current to flow through the transistor, the value of the base current IB is calculated by using the below formula:


Where ‘IB’ is the base current

‘IC’ is the collector current. ‘hFE’ is the transistor’s current gain, which is assumed as 50. In some cases, it is shown as ‘β’

In the given circuit, for an 800mA collector current, 16mA of base current is needed to be allowed to the base resistor. The value of the base resistor is calculated using the below formula:

RB = (VCC -VBE) / IB

Where ‘VCC’ is the operating voltage of the load= 12V

‘VBE’ is the voltage between the emitter and base terminals of the transistor, which is taken as 1.3V (from the datasheet). Therefore, the value of ‘RB’ will be,

RB = (12-1.3) /(16×10^-3)

RB = 660 Ohms

But, this value is not accurate because the transistor had an inherent voltage drop across the collector current. Hence, getting the maximum current value is an experiment. Here this formula will help to reach the closest value to start with it.


The advantages of a 2N2219 transistor include the following.

  • It can operate at high voltages.
  • It is a low-power signal transistor.
  • More efficient as compared to 2N222.
  • As it is a current-controlled device, it uses less current in the range of 10 to 20 microamps to control high current flow throughout the emitter & base terminals.

Where to Use/Applications:

A few applications of a 2N2219 transistor are listed below.

  • Used in driver modules like an LED driver, relay driver, and many more.
  • Used in Darlington pair configurations.
  • Used in amplifier modules like signal amplifiers, audio amplifiers, power amplifiers, and many more.
  • Used in switching applications.
  • Used in small-signal amplification.

Please refer to this link for the 2N2219 Transistor Datasheet.

Thus, the low voltage and high current of the 2N2219 NPN transistor make it ideal for high-speed switching circuit applications and the number of electrons used for the amplifying purpose is controlled by its base terminal. Here is a question for you, what is the function of a 2n4401 transistor? “