I. Product Overview

The 2N3904 is a classic NPN-type bipolar transistor widely used in various electronic circuits. Thanks to its excellent performance, reliability and broad applicability, it ranks among the preferred components for electronic engineers in circuit design. Whether for signal amplification, switch control, frequency oscillation or other application scenarios, the 2N3904 delivers stable and efficient performance, serving as an indispensable core component in electronic equipment.

II. Product Characteristics

(1) Electrical Parameters

Collector-Emitter Breakdown Voltage (Vceo): 40V The 2N3904 can withstand a collector-emitter voltage up to 40 V. It operates stably under a wide range of supply-voltage conditions, covering low-voltage portable devices as well as higher-voltage power circuits. It ensures safe circuit operation and effectively prevents device damage caused by excessive voltage.

Collector Current (Ic): 200mA This transistor supports a maximum collector current of 200 mA, offering sufficient current-driving capability to satisfy most medium-and-low-power circuit requirements. Typical uses include driving small-size motors, controlling LED banks, or acting as the output stage of audio amplifier circuits, delivering stable and robust circuit outputs.

Power Dissipation (Pd): 625mW Under normal operating conditions, the 2N3904 can dissipate power up to 625 mW. It can work reliably within certain current and voltage ranges without suffering thermal damage. This power rating suits many common applications, such as functioning as a switching element in digital circuits or performing signal amplification in analog circuits, while guaranteeing circuit reliability and stability.

Collector Cut-off Current (Icbo): Low The 2N3904 features very low collector cut-off current, meaning negligible leakage current under cut-off conditions. This characteristic is critical for precise circuit control and low-power operation. Especially for applications requiring high-precision signal processing or low-power design, such as sensor-signal amplifier circuits and battery-powered portable devices, it effectively reduces static power consumption and improves overall system efficiency.

Transition Frequency (fT): 300MHz Boasting a transition frequency as high as 300 MHz, the 2N3904 exhibits outstanding high-frequency response. In high-frequency circuit applications including radio-frequency (RF) circuits, high-speed digital circuits and high-frequency oscillators, it responds rapidly to signal variations with favorable frequency characteristics. It preserves signal integrity and accuracy and meets stringent high-frequency performance requirements of modern electronic equipment.

Operating Temperature: +150℃ (Tj) The transistor can operate normally at a junction temperature up to +150 ℃, enabling deployment in harsh environmental conditions. Whether in high-temperature industrial settings, automotive electronic systems or other devices requiring stable high-temperature operation, the 2N3904 maintains consistent performance, secures circuit reliability and stability, and extends equipment service life.

(2) Package Form

The 2N3904 is commonly supplied in the TO-92 package. This package features compact size, favorable thermal dissipation and convenient mounting. TO-92 packaged transistors can be directly inserted into breadboards or soldered onto printed circuit boards (PCBs), facilitating circuit prototyping and debugging. Its good thermal performance also helps maintain stable device operation under high-power or high-temperature conditions and ensures reliable circuit performance.

(3) Application Fields

Signal Amplification The 2N3904 is widely adopted in audio, video and other signal-amplifier circuits. With low cut-off current and high transition frequency, it amplifies weak signals precisely while preserving signal integrity and fidelity, supporting high-quality audio and video transmission.

Switch Control In digital circuits, the 2N3904 works as a switching element to turn other electronic components on and off. Owing to its low cut-off current and high collector-current capability, it switches states rapidly and accurately for precise circuit control, and plays an important role in relay-drive circuits, motor-control circuits and more.

Oscillator Circuits Leveraging its high-frequency characteristics, the 2N3904 can be used to construct oscillator circuits such as crystal oscillators and RC oscillators. It generates stable high-frequency signals to provide accurate clock references for clock circuits and communication equipment, ensuring synchronized device operation and reliable data transmission.

Power Supply Circuits Within power-supply circuits, the 2N3904 may be used to build linear regulator circuits or serve as a control element for switching power supplies. Its high collector-current capacity and low cut-off current enable effective power-output control. It guarantees power-supply stability and reliability and delivers steady power for diverse electronic devices.