2N5551 Transistor: Pinout, Datasheet, and Applications
Bipolar Transistors - BJT NPN Gen Pur SS
The central semiconductor 2N5551 is a silicon NPN transistor designed for high voltage amplifier applications.

AC Line detector using transistor 2n5551 , a useful tool
2N5551 Description
The 2N5551 is an NPN high-voltage transistor in a TO-92 plastic package. It's PNP complements are 2N5400 and 2N5401. The 2N5551 is built to use in general purpose applications such as amplification and switching. The maximum collector to emitter voltage is 160V, and the maximum collector to base voltage is 180V, making it easy to use in circuits with a voltage below 160V. The maximum output load this transistor can handle is 600mA and the maximum power consumption of the collector is 625mW.
2N5551 Pinout

2N5551 CAD Model
Symbol

Footprint

3D Model

2N5551 Features
Package Type: TO-92
Transistor Type: NPN
Max Collector Current(IC): 6A or 600mA
Max Collector-Emitter Voltage (VCE): 160V
Max Collector-Base Voltage (VCB): 180V
Max Emitter-Base Voltage (VBE): 6V
Max Collector Dissipation (Pc): 625 mW
Max Transition Frequency (fT): 100 MHz
Minimum & Maximum DC Current Gain (hFE): 80 - 250
Max Storage & Operating temperature Should be: -55 to +150 Centigrade
Specifications
- TypeParameter
- Factory Lead Time8 Weeks
- Mount
In electronic components, the term "Mount" typically refers to the method or process of physically attaching or fixing a component onto a circuit board or other electronic device. This can involve soldering, adhesive bonding, or other techniques to secure the component in place. The mounting process is crucial for ensuring proper electrical connections and mechanical stability within the electronic system. Different components may have specific mounting requirements based on their size, shape, and function, and manufacturers provide guidelines for proper mounting procedures to ensure optimal performance and reliability of the electronic device.
Through Hole - Package / Case
refers to the protective housing that encases an electronic component, providing mechanical support, electrical connections, and thermal management.
TO-92 - Collector-Emitter Breakdown Voltage160V
- Collector-Emitter Saturation Voltage200mV
- hFEMin80
- Power Dissipation (Max)625mW
- Number of Elements1
- Published2012
- Packaging
Semiconductor package is a carrier / shell used to contain and cover one or more semiconductor components or integrated circuits. The material of the shell can be metal, plastic, glass or ceramic.
Bulk - JESD-609 Code
The "JESD-609 Code" in electronic components refers to a standardized marking code that indicates the lead-free solder composition and finish of electronic components for compliance with environmental regulations.
e0 - Pbfree Code
The "Pbfree Code" parameter in electronic components refers to the code or marking used to indicate that the component is lead-free. Lead (Pb) is a toxic substance that has been widely used in electronic components for many years, but due to environmental concerns, there has been a shift towards lead-free alternatives. The Pbfree Code helps manufacturers and users easily identify components that do not contain lead, ensuring compliance with regulations and promoting environmentally friendly practices. It is important to pay attention to the Pbfree Code when selecting electronic components to ensure they meet the necessary requirements for lead-free applications.
no - Part Status
Parts can have many statuses as they progress through the configuration, analysis, review, and approval stages.
Active - Number of Terminations3
- ECCN Code
An ECCN (Export Control Classification Number) is an alphanumeric code used by the U.S. Bureau of Industry and Security to identify and categorize electronic components and other dual-use items that may require an export license based on their technical characteristics and potential for military use.
EAR99 - Terminal Finish
Terminal Finish refers to the surface treatment applied to the terminals or leads of electronic components to enhance their performance and longevity. It can improve solderability, corrosion resistance, and overall reliability of the connection in electronic assemblies. Common finishes include nickel, gold, and tin, each possessing distinct properties suitable for various applications. The choice of terminal finish can significantly impact the durability and effectiveness of electronic devices.
Tin/Lead (Sn/Pb) - Max Operating Temperature
The Maximum Operating Temperature is the maximum body temperature at which the thermistor is designed to operate for extended periods of time with acceptable stability of its electrical characteristics.
150°C - Min Operating Temperature
The "Min Operating Temperature" parameter in electronic components refers to the lowest temperature at which the component is designed to operate effectively and reliably. This parameter is crucial for ensuring the proper functioning and longevity of the component, as operating below this temperature may lead to performance issues or even damage. Manufacturers specify the minimum operating temperature to provide guidance to users on the environmental conditions in which the component can safely operate. It is important to adhere to this parameter to prevent malfunctions and ensure the overall reliability of the electronic system.
-65°C - HTS Code
HTS (Harmonized Tariff Schedule) codes are product classification codes between 8-1 digits. The first six digits are an HS code, and the countries of import assign the subsequent digits to provide additional classification. U.S. HTS codes are 1 digits and are administered by the U.S. International Trade Commission.
8541.21.00.95 - Terminal Position
In electronic components, the term "Terminal Position" refers to the physical location of the connection points on the component where external electrical connections can be made. These connection points, known as terminals, are typically used to attach wires, leads, or other components to the main body of the electronic component. The terminal position is important for ensuring proper connectivity and functionality of the component within a circuit. It is often specified in technical datasheets or component specifications to help designers and engineers understand how to properly integrate the component into their circuit designs.
BOTTOM - Peak Reflow Temperature (Cel)
Peak Reflow Temperature (Cel) is a parameter that specifies the maximum temperature at which an electronic component can be exposed during the reflow soldering process. Reflow soldering is a common method used to attach electronic components to a circuit board. The Peak Reflow Temperature is crucial because it ensures that the component is not damaged or degraded during the soldering process. Exceeding the specified Peak Reflow Temperature can lead to issues such as component failure, reduced performance, or even permanent damage to the component. It is important for manufacturers and assemblers to adhere to the recommended Peak Reflow Temperature to ensure the reliability and functionality of the electronic components.
NOT SPECIFIED - Time@Peak Reflow Temperature-Max (s)
Time@Peak Reflow Temperature-Max (s) refers to the maximum duration that an electronic component can be exposed to the peak reflow temperature during the soldering process, which is crucial for ensuring reliable solder joint formation without damaging the component.
NOT SPECIFIED - Pin Count
a count of all of the component leads (or pins)
3 - JESD-30 Code
JESD-30 Code refers to a standardized descriptive designation system established by JEDEC for semiconductor-device packages. This system provides a systematic method for generating designators that convey essential information about the package's physical characteristics, such as size and shape, which aids in component identification and selection. By using JESD-30 codes, manufacturers and engineers can ensure consistency and clarity in the specification of semiconductor packages across various applications and industries.
O-PBCY-T3 - Qualification Status
An indicator of formal certification of qualifications.
Not Qualified - Polarity
In electronic components, polarity refers to the orientation or direction in which the component must be connected in a circuit to function properly. Components such as diodes, capacitors, and LEDs have polarity markings to indicate which terminal should be connected to the positive or negative side of the circuit. Connecting a component with incorrect polarity can lead to malfunction or damage. It is important to pay attention to polarity markings and follow the manufacturer's instructions to ensure proper operation of electronic components.
NPN - Element Configuration
The distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals.
Single - Transistor Application
In the context of electronic components, the parameter "Transistor Application" refers to the specific purpose or function for which a transistor is designed and used. Transistors are semiconductor devices that can amplify or switch electronic signals and are commonly used in various electronic circuits. The application of a transistor can vary widely depending on its design and characteristics, such as whether it is intended for audio amplification, digital logic, power control, or radio frequency applications. Understanding the transistor application is important for selecting the right type of transistor for a particular circuit or system to ensure optimal performance and functionality.
AMPLIFIER - Gain Bandwidth Product
The gain–bandwidth product (designated as GBWP, GBW, GBP, or GB) for an amplifier is the product of the amplifier's bandwidth and the gain at which the bandwidth is measured.
300MHz - Collector Emitter Voltage (VCEO)
Collector-Emitter Voltage (VCEO) is a key parameter in electronic components, particularly in transistors. It refers to the maximum voltage that can be applied between the collector and emitter terminals of a transistor while the base terminal is open or not conducting. Exceeding this voltage limit can lead to breakdown and potential damage to the transistor. VCEO is crucial for ensuring the safe and reliable operation of the transistor within its specified limits. Designers must carefully consider VCEO when selecting transistors for a circuit to prevent overvoltage conditions that could compromise the performance and longevity of the component.
200mV - Max Collector Current
Max Collector Current is a parameter used to specify the maximum amount of current that can safely flow through the collector terminal of a transistor or other electronic component without causing damage. It is typically expressed in units of amperes (A) and is an important consideration when designing circuits to ensure that the component operates within its safe operating limits. Exceeding the specified max collector current can lead to overheating, degradation of performance, or even permanent damage to the component. Designers must carefully consider this parameter when selecting components and designing circuits to ensure reliable and safe operation.
600mA - Transition Frequency
Transition Frequency in electronic components refers to the frequency at which a device can transition from one state to another, typically defining the upper limit of its operating frequency. It is a critical parameter in determining the speed and performance of active components like transistors and integrated circuits. This frequency is influenced by factors such as capacitance, resistance, and the inherent characteristics of the materials used in the component's construction. Understanding transition frequency is essential for optimizing circuit designs and ensuring reliable signal processing in various applications.
100MHz - Frequency - Transition
The parameter "Frequency - Transition" in electronic components refers to the maximum frequency at which a signal transition can occur within the component. It is a crucial specification for digital circuits as it determines the speed at which data can be processed and transmitted. A higher frequency transition allows for faster operation and better performance of the electronic component. It is typically measured in hertz (Hz) or megahertz (MHz) and is specified by the manufacturer to ensure proper functioning of the component within a given frequency range.
300MHz - Collector Base Voltage (VCBO)
Collector Base Voltage (VCBO) is the maximum allowable voltage that can be applied between the collector and base terminals of a bipolar junction transistor when the emitter is open. It is a critical parameter that determines the voltage rating of the transistor and helps prevent breakdown in the collector-base junction. Exceeding this voltage can lead to permanent damage or failure of the component.
180V - Emitter Base Voltage (VEBO)
Emitter Base Voltage (VEBO) is a parameter used in electronic components, particularly in transistors. It refers to the maximum voltage that can be applied between the emitter and base terminals of a transistor without causing damage to the device. Exceeding this voltage limit can lead to breakdown of the transistor and potential failure. VEBO is an important specification to consider when designing circuits to ensure the proper operation and reliability of the components. It is typically provided in the datasheet of the transistor and should be carefully observed to prevent any potential damage during operation.
6V - DC Current Gain-Min (hFE)
The parameter "DC Current Gain-Min (hFE)" in electronic components refers to the minimum value of the DC current gain of a bipolar junction transistor (BJT). It is a measure of how much the transistor amplifies the input current to produce the output current. The hFE value indicates the ratio of the output current to the input current when the transistor is operating in the active region. A higher hFE value signifies a higher current gain and better amplification capabilities of the transistor. It is an important parameter to consider when designing and analyzing transistor circuits for various electronic applications.
80 - Continuous Collector Current
Continuous Collector Current is the maximum amount of current that a transistor can continuously carry through its collector terminal without overheating or being damaged. This parameter is crucial for designing circuits as it determines the suitability of a transistor for specific applications. Exceeding this value can lead to reduced performance or failure of the component. It is typically specified in amperes (A) and varies based on the transistor's construction and cooling conditions.
600mA - RoHS Status
RoHS means “Restriction of Certain Hazardous Substances” in the “Hazardous Substances Directive” in electrical and electronic equipment.
RoHS Compliant
2N5551 Circuit

2N5551 Alternatives

2N5551 PNP Complementary
2N5400 and 2N5401
Where to use 2N5551
The 2N5551 is an NPN amplifier transistor with an amplification factor (hfe) of 80 when the collector current is 10mA. It also has decent switching characteristics (transition frequency is 100MHz) hence can amplify low-level signals.
Due to this feature, the transistor is commonly used for amplification of audio or other low power signals. So if you are looking for an NPN transistor for you amplifier circuit then this transistor might be the right choice.
How to use 2N5551
The 2N5551 NPN transistor is widely used for amplification. A very simple bare minimum circuit for a transistor to work as an amplifier is shown below. The simulation graph that shows the amplified output sine wave can also be found.

Here the input sine wave of magnitude 8mV (yellow colour) is amplified to 50mV (Pink colour) as shown in the graph. In the above circuit the resistors R3 and R4 form a potential divider which decides the Emitter -Base voltage (VBE). The Resistor R1 is the load resistor and the resistor R2 is the emitter resistor. Changing the value of RL will affect the amplification of the output wave.
A transistor is normally a current amplifier, meaning the current flowing though the base will be amplified in the current flowing through the collector. This amplification depends on the amplification factor (hfe) which is 80 for 2N5551. This means that the collector current will be amplified by 80 times than that of the base current.
Ic = βIb
Another current that we've brought into consideration is the emitter current (IE), but due to transistor action we assume that the value of Emitter current is almost equal to Collector current, however the difference between the both can be found with the value of α. Normally, the value of collector current is given by
IE = IC + IB
The output is obtained across the collector which is the Collector-Emitter voltage (VCE). This output voltage depends on the Input voltage (Vcc, here 12V) without the voltage drop across the loads resistor (R1). Therefore the output voltage Vout can be given as
Vout = VCE = (Vcc – IcRc)
2N5551 Applications
Low power amplifiers
Current amplifiers
Small signal boosters
Audio or other signal amplifiers
Darlington pair
2N5551 Package

2N5551 Manufacturer
Since 1974, Central Semiconductor has manufactured innovative discrete semiconductors used in electronic products worldwide. Devices currently include standard and custom small signal transistors, bipolar power transistors, MOSFETs, diodes, rectifiers, protection devices, current limiting diodes, bridge rectifiers, thyristors, and silicon carbide devices. Central’s devices are available in industry standard surface mount and through-hole packages, bare die, TLMs (Tiny Leadless Modules™), and MDMs (Multi Discrete Modules™). Central has earned a reputation as a manufacturer of the highest quality products consistently delivered on-time, and a provider of exceptional value-added services.
Trend Analysis
Datasheet PDF
- ReachStatement :
- Datasheets :
1.What is 2N5551?
2N5551 is an NPN bipolar junction transistor which is mainly used for general purpose amplification and gas discharge display drivers. It consists of three terminals known as the emitter, base, and collector and comes in a TO-92 package.
2.What are the two main applications of transistors?
Transistors are commonly used in digital circuits as electronic switches which can be either in an "on" or "off" state, both for high-power applications such as switched-mode power supplies and for low-power applications such as logic gates.
3.What are the common types of transistors?
Transistors are basically classified into two types. They are: Bipolar Junction Transistors (BJT) and Field Effect Transistors (FET). The BJTs are again classified into NPN and PNP transistors. The FET transistors are classified into JFET and MOSFET.
4.How to safely long run 2N5551 in a circuit?
To get performance from this transistor and make it run long term in an electronic circuit it is suggested to not provide voltage above 160V to this transistor, and stay 5V to 10V below from maximum ratings to be safe. Always use a suitable base resistor to provide required base current, do not operate load above 600mA and always store or operate in temperature above -55 centigrade and below +150 centigrade.
5.Does all NPN transistors work in the same way? Are the only differences in all the models just the rating currents and voltages?
There are two ways to see whether one transistor will substitute for another in a specific application. 1) Compare the transistor ratings. 2) Compare the new proposed transistor with the application requirements. Even if the second transistor is inferior to the first, if it meets the requirements of the application, it will still be OK.
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