Part Number: 2N3904BU

Manufacturer: onsemi / Fairchild

Description: Bipolar Transistors – BJT NPN Transistor General Purpose

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Technical Specifications of 2N3904BU

Datasheet  2N3904BU datasheet
Category Discrete Semiconductor Products
Family Transistors – Bipolar (BJT) – Single
Manufacturer Fairchild Semiconductor
Packaging Bulk
Transistor Type NPN
Current – Collector (Ic) (Max) 200mA
Voltage – Collector Emitter Breakdown (Max) 40V
Vce Saturation (Max) @ Ib, Ic 300mV @ 5mA, 50mA
Current – Collector Cutoff (Max)
DC Current Gain (hFE) (Min) @ Ic, Vce 100 @ 10mA, 1V
Power – Max 625mW
Frequency – Transition 300MHz
Mounting Type Through Hole
Package / Case TO-226-3, TO-92-3 (TO-226AA)
Supplier Device Package TO-92-3

The 2N3904BU is a transistor, which is a type of semiconductor device that can switch or amplify electrical signals. Transistors may be found in almost all modern electronic devices. The base, the Collector, and the emitter are the three primary components that constitute a transistor. The voltage that controls whether or not current travels from the Collector to the emitter is applied at the base of the transistor. It can be used as either an amplifier or a switching device while current flows from the Collector to the emitter. Keep reading if you want to find out more about this device.

2N3904BU Description

Because the 2N3904 is an NPN transistor, its Collector and emitter will remain open (in a state known as reverse bias) when the base pin is connected to the ground. However, when a signal is applied to the base pin, it will close (in a state known as forwarding bias). The gain value of the 2N3904 transistor is 300, which controls the amplification capacity of the transistor.

This transistor cannot be used to connect loads that require more than 200 milliamperes of current because the maximum amount of current that could travel via the Collector pin is just 200 milliamperes. To bias a transistor, we need to supply current to the base pin, and the current amount should not exceed 5 milliamperes (mA).

When this transistor is fully biased, it can let a current of up to 200 mA travel between the Collector and the emitter. This stage is referred to as the Saturation Region. The voltage allowed to be applied across the Collector-Emitter (VCE) or Collector-Base (VCB) could be 40V or 60V, respectively. When the base current is eliminated, the transistor turns off completely. This stage is referred to as the Cut-off Region, and the Base Emitter voltage can be close to 600 mV at this point.

2N3904 as a switch

As mentioned earlier, the Saturation and Cut-Off Region is where a transistor is operated when it serves its purpose as a switch. As was previously mentioned, a transistor will behave as a switch that is open when subjected to forward bias, and it will act as a switch that is closed when subjected to reverse bias. This biasing can be performed by applying the necessary current to the base pin. As was previously stated, the biasing current should not exceed 5 mA. Because the transistor will be destroyed by currents greater than 5 milliamperes, a resistor is always supplied in series with the base pin. The value of this resistor, denoted by RB, can be determined by utilizing the formulas provided below.

RB  = VBE / IB

The value of VBE ought to be 5V for 2N3904, and the Base current (IB is dependent on the current flowing through the Collector) (IC). It is essential to keep the value of IB below mA.

2N3904 as Amplifier

When it is operating in its Active Region, a Transistor performs the function of an Amplifier. In various designs, it can amplify power, voltage, and current.

The following is a list of some of the configurations that can be found in amplifier circuits:

  1. Common Emitter Amplifier
  2. Common Collector Amplifier
  3. Common Base Amplifier

The most frequent and widespread setup is the common emitter type, which may be seen in the examples given above. Calculating the DC gain of the transistor when it is being used in an amplifier may be done with the help of the following formulas.

DC Current Gain is Calculated by Comparing the Collector Current (IC) to the Base Current (IB)

2N3904BU Features

2N3904BU Features

  • A high voltage NPN transistor designed for general purpose applications is denoted by the part number 2N3904BU. It is not necessary to use a heat sink because it can manage voltages of up to 200 volts and can handle a maximum collector current of 1.5 amps.
  • A high voltage NPN transistor designed for general purpose applications is denoted by the part number 2N3904BU. It is not necessary to use a heat sink because it can manage voltages of up to 200 volts and can handle a maximum collector current of 1.5 amps.
  • It is pretty simple to use this component in various circuits because it does not need any additional components or resistors to be employed to set its working parameters.
  • This component comes in TO-92 packaging, is RoHS compliant, and has an operational temperature range from -55 degrees Celsius to +150 degrees Celsius.

2N3904BU Applications

  • It is utilized in Driver Modules such as Relay Driver, LED driver, and others.
  • It is utilized in various amplifier modules, including signal amplifiers, audio amplifiers, and others.
  • Since the VCB and VBE are high, they are suitable for controlling voltage loads up to 40 V.
  • It is often used in televisions and a variety of other home appliances.

2N3904BU Manufacturer

on-semiconductor (nasdaq: on) is at the forefront of energy-efficient innovation, providing clients with the tools necessary to curb overall energy use. The company provides design engineers with a wide range of energy-efficient power and signal management, discrete, logic, and custom solutions to help them overcome their unique design challenges in a variety of application areas, such as automotive, computing, communications, consumer, led lighting, medical, aerospace, military, industrial, and power supply.

The supply chain and quality management system managed by On Semiconductor is incredibly responsive, dependable, and top-notch. The business also maintains a network of production facilities, sales offices, and design centers in important international markets like North America, Europe, and the Asia Pacific.


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