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2N4401 Transistor Introduction

2N4401 is a common transistor, which has some very good functions in its small package. The maximum collector current is 500 mA, which is enough to drive many loads in the circuit.

What is 2N4401 Transistor

2N4401 is an NPN transistor, so when the base pin is grounded, the collector and emitter will remain disconnected (reverse bias), and when a signal is supplied to the base pin, the collector and emitter will be closed (forward bias). The gain value H Fe of 2N4401 is 500, which determines the amplification ability of the transistor. The maximum current flowing through the collector pin is 800mA, so we cannot use the transistor connection to consume more than 500mA load. In order to bias the transistor, we have to supply current to the base pin, which should be limited to 5mA.

When the transistor is fully biased, it allows a maximum current of 800 Ma to flow through the collector and emitter. This stage is called saturation region, and the typical voltage allowed for cross collector emitter (V ­ CE) or base emitter (v be) is 200 and 900 MV respectively. When the base current is removed, the transistor is completely cut off. This stage is called cut-off region, and the base emitter voltage may be about 660 MV.

The TO-92 package of the transistor has many excellent characteristics, making it an ideal TO-92 transistor in the laboratory.

2N4401 datasheet

2N4401 Pinout &Configuration

2N4401 has three terminals, as shown in the table.

Pin NumberPin NameDescription
1EmitterCurrent Drains out through emitter, normally connected to ground
2BaseControls the biasing of transistor, Used to turn ON or OFF the transistor
3CollectorCurrent flows in through collector, normally connected to load
2N4401 Pinout &Configuration

2N4401 Features

  1. Package Type: TO-92
  2. Transistor Type: NPN
  3. Max Collector Current(IC): 500mA
  4. Max Collector-Emitter Voltage (VCE): 40V
  5. Max Collector-Base Voltage (VCB): 60V
  6. Max Emitter-Base Voltage (VEBO): 6V
  7. Max Collector Dissipation (Pc): 625 miliWatt
  8. Max Transition Frequency (fT): 250 MHz
  9. Minimum & Maximum DC Current Gain (hFE): 20 – 300
  10. Max Storage & Operating temperature Should Be: -55 to +150 Centigrade

2N4401 equivalent transistor

  • The 2N4401 equivalent transistors are: 2N2222, P2N2222A, ECG123AP, BC537, BC538
  • The 2N4401 pnp complementary is: 2N4403

How does a 2N4401 transistor work?

As mentioned above, the transistor has good functions and can be used in various electronic applications. For example, it can be used to drive many loads in electronic circuits, such as high-power relay, few high-power LEDs below 500mA, many small LEDs, another part of LED. Circuit, high power transistor and so on. In addition to these applications, it can also perform well in audio preamplifier circuits and audio amplifier levels. In addition, it can also be used in the output of small audio amplifiers to increase the output power to drive small loudspeakers of 200MW to 2W. Through these applications, it can also be used to make Darlington pairs, and many BJT transistors with similar characteristics can be used to replace the transistors.

This transistor like all can be used either as a switch or as an amplifier. The Base-Emitter voltage of this transistor is 6V so you just have to supply this voltage across the base and emitter of the transistor to induce a base current into the transistor. This transistor will make it forward biased and thus closes the connection between collector and emitter. However one important thing to notice is the Base resistor a.k.a current limiting resistor. As the name suggests this resistor will limit the current flowing through the transistor to prevent it from damaging. The value for this resistor can be calculated using the formula


To make things simple I have shown a simplified circuit to make a transistor as switch. In actual circuit modifications might be required. I have used a base voltage of 5V and a value of 1K as current limiting resistor 


Note that the motor here draws about 500mA from the 12V power source, since the 2N4401 has collector current rating upto 500mA this circuit is possible had it been a BC547 the transistor should have been burnt.

2N4401 Applications

  • Sensor Circuits
  • Audio Preamplifiers
  • Audio Amplifier Stages
  • Switching Loads under 500mA
  • Motor speed control
  • Darlington Pairs
  • RF circuits under 250MHz

That’s all for today. Hope you enjoyed this article. However, if you have doubts or have any questions about this, you can contact me in the comments section below. I’ll be happy to help you as best I can. Let us know your feedback and suggestions at any time, they allow us to provide you with high-quality work that responds to your needs and expectations, and helps you continue to give back to our products. Thank you for reading this article.

3Celectrons also provide this kind of parts, if you are interested in, just contact us!

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