2N5551 NPN High-Voltage Transistor

Overview

The 2N5551 is a general-purpose NPN bipolar junction transistor (BJT) designed for high-voltage applications. Housed in a TO-92 (SOT54) plastic package, this transistor is widely used in amplification and switching circuits where elevated voltage handling is required. With a maximum collector-emitter voltage (V_CEO) of 160V and a collector current (I_C) rating of 300mA, the 2N5551 is suitable for low-power applications demanding robust voltage tolerance.

This transistor is characterized by its high DC current gain, low noise, and reliable performance across a broad range of operating conditions. Its compact TO-92 package makes it easy to integrate into through-hole PCB designs, while its electrical characteristics ensure stable operation in both analog and digital circuits.

Features

• High Voltage Capability: Maximum V_CEO of 160V, making it suitable for high-voltage circuits.
• Low Current Operation: Maximum collector current (I_C) of 300mA, ideal for small-signal applications.
• High DC Current Gain (h_FE): Typically ranges from 80 to 250, ensuring efficient signal amplification.
• Low Noise: Optimized for use in audio and sensitive signal processing circuits.
• TO-92 Package: Compact and widely compatible with through-hole PCB designs.
• Reliable Performance: Stable operation across temperature and voltage variations.

Applications

The 2N5551 is versatile and finds use in a variety of electronic circuits, including:

• High-Voltage Switching: Used in power supply circuits and relay drivers.
• Signal Amplification: Suitable for audio amplifiers, preamplifiers, and RF stages.
• Voltage Regulation: Employed in linear regulator circuits and voltage reference designs.
• Oscillators and Timers: Integrated into waveform generators and timing circuits.
• General-Purpose Switching: Functions as a switch in low-power digital and analog systems.

Electrical Characteristics

The following tables outline the key electrical specifications of the 2N5551 transistor under typical operating conditions (unless otherwise specified).

Absolute Maximum Ratings

• Collector-Emitter Voltage (V_CEO): 160V
• Collector-Base Voltage (V_CBO): 180V
• Emitter-Base Voltage (V_EBO): 6V
• Collector Current (I_C): 300mA (continuous)
• Total Power Dissipation (P_tot): 625mW at 25°C
• Operating Junction Temperature (T_j): -55°C to +150°C
• Storage Temperature (T_stg): -55°C to +150°C

DC Current Gain (h_FE)

• Test Condition: I_C = 10mA, V_CE = 5V
• Minimum h_FE: 80
• Typical h_FE: 120
• Maximum h_FE: 250

Transition Frequency (f_T)

• Test Condition: I_C = 10mA, V_CE = 5V, f = 100MHz
• Typical f_T: 100MHz

Noise Figure (NF)

• Test Condition: I_C = 100µA, V_CE = 5V, f = 1kHz
• Typical NF: 5dB

Package Information

The 2N5551 is housed in a TO-92 (SOT54) plastic package, which is a through-hole mounting style with three leads. The package dimensions and pin configuration are as follows:

TO-92 Package Dimensions

• Body Length: 4.58mm (max)
• Body Width: 3.81mm (max)
• Body Height: 4.70mm (max)
• Lead Spacing: 2.54mm (between adjacent leads)

Pin Configuration

• Pin 1 (Emitter): Connected to the emitter region of the transistor.
• Pin 2 (Base): Controls the transistor's conductivity.
• Pin 3 (Collector): Collects charge carriers and is the output terminal.

Thermal Characteristics

• Thermal Resistance, Junction-to-Ambient (R_θJA): 200°C/W
• Thermal Resistance, Junction-to-Case (R_θJC): 83.3°C/W

Conclusion

The 2N5551 is a reliable NPN transistor optimized for high-voltage, low-current applications. Its combination of high DC current gain, low noise, and robust voltage tolerance makes it a versatile choice for amplification, switching, and regulation tasks. The TO-92 package ensures ease of integration into a wide range of electronic designs, while its electrical characteristics provide stable performance under varying conditions. Whether used in audio circuits, power supplies, or timing applications, the 2N5551 delivers consistent and efficient operation.