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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi 2N5551TAR

Name: 2N5551TAR
Brand: onsemi
SKU: 2N5551TAR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N5551TAR

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Datasheet:: 2N5551TAR.pdf

Description:: TRANS NPN 160V 0.6A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2N5551TAR from ON Semiconductor is an NPN general-purpose amplifier transistor designed for high-voltage amplification and gas discharge display driver circuits. It features a 160 V collector-emitter breakdown voltage (V_CEO), 600 mA continuous collector current (I_C), and 625 mW power dissipation in TO-92 package - enabling use in line-powered signal conditioning and indicator driving applications.

For engineers reviewing the 2N5551TAR datasheet, pinout, applications, or equivalent options, key selection criteria include its high-voltage capability (160 V V_CEO), DC current gain range (80–250 at I_C = 10 mA), low saturation voltage (0.15 V at I_C = 10 mA / I_B = 1 mA), and thermal resistance (200 °C/W junction-to-ambient) - all critical for reliable operation in industrial interface and analog front-end designs.

Technical Context

This device operates as a discrete NPN bipolar junction transistor with fixed emitter-base and collector-base junction structures. Its design supports linear amplification up to 100 MHz f_T, exhibits low noise figure (8.0 dB at 10 Hz–15.7 kHz), and maintains stable h_FE across ambient temperatures from –55 °C to +150 °C.

The 2N5551TAR uses a standard TO-92 3-lead through-hole package with Emitter–Collector–Base pinout (Pin 1: Emitter, Pin 2: Collector, Pin 3: Base). Its absolute maximum ratings are defined by junction temperature limits (150 °C) and derating curves (5.0 mW/°C above 25 °C), ensuring predictable thermal behavior in PCB-mounted applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	160 V - Enables safe operation in 120 V AC line-referenced circuits and high-side switching up to 100 V DC bus.
I_C (continuous)	600 mA - Supports driving medium-current loads such as LED arrays, relay coils, or small solenoids without external heat sinking.
h_FE	80–250 (at I_C = 10 mA, V_CE = 5 V) - Provides sufficient DC gain for single-stage amplification or switch biasing with margin for process variation.
V_CE(sat)	0.15 V (at I_C = 10 mA, I_B = 1 mA) - Minimizes conduction loss and self-heating in saturated-switch applications.
f_T	100 MHz - Supports RF pre-amplifier stages and fast-switching digital interface circuits up to ~10 MHz square-wave operation.
P_D	625 mW (at T_A = 25 °C) - Delivers usable power handling in compact TO-92 footprint without forced airflow or heatsinking.

Pinout & Package

2N5551TAR is housed in a JEDEC TO-92 3-lead molded plastic package with straight leads and center-collector configuration (suffix "-C" per ordering info). The case is non-polarized, thermally conductive via leadframe, and rated for manual or wave-solder assembly.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to ground or low-impedance return path; defines reference for base drive and collector load placement.
2 (Collector)	High-voltage output terminal	Interfaces with load (e.g., display segment anode, relay coil) and withstands up to 160 V relative to emitter.
3 (Base)	Control input terminal	Receives current-limited drive (typically 1–10 mA) to saturate or linearly bias the transistor; requires series resistor for TTL/CMOS interfacing.

Key Features

Feature	Design Value
High V_CEO rating	160 V - Allows direct connection to 100 V DC rails or rectified AC lines without additional voltage clamping.
Low V_CE(sat)	0.15 V at 10 mA - Reduces power loss and thermal stress during switching, improving efficiency in driver stages.
Wide h_FE range	80–250 - Accommodates production spread while maintaining functional margin in both analog and digital bias networks.
100 MHz f_T	Supports broadband amplification and fast edge-rate switching in pulse generator and timing circuits.
–55 °C to +150 °C operating range	Validated for deployment in industrial control cabinets, outdoor lighting ballasts, and automotive under-hood auxiliary modules.

Applications

Gas Discharge Display Driver	High-Voltage Signal Amplifier
Use Scenario: Driving individual segments of neon or Nixie tube displays powered from 100–150 V DC supplies. IC Role / Device Role / Timing Role: NPN switch controlling current flow through display cathodes/anodes with precise on/off timing. Use Value: 160 V V_CEO ensures safe operation at display supply voltage; low V_CE(sat) minimizes power dissipation during active segment illumination.	Use Scenario: Amplifying sensor signals (e.g., piezoelectric transducers, photomultiplier outputs) referenced to high-voltage bias rails. IC Role / Device Role / Timing Role: Linear NPN amplifier stage providing gain before ADC input or comparator threshold detection. Use Value: 100 MHz f_T and 8.0 dB noise figure preserve signal integrity; wide h_FE range simplifies bias network design across production lots.
Relay Coil Driver	Industrial Interface Buffer
Use Scenario: Switching 24–48 V DC relays in PLC output modules or HVAC control panels. IC Role / Device Role / Timing Role: Saturated switch delivering >500 mA coil current with minimal voltage drop and thermal rise. Use Value: 600 mA I_C rating and 625 mW P_D support continuous relay actuation without derating; TO-92 form factor enables dense board layout.	Use Scenario: Level-shifting and isolating logic signals between microcontroller I/O and 12–24 V field buses (e.g., 4–20 mA transmitter interfaces). IC Role / Device Role / Timing Role: Discrete transistor buffer providing galvanic separation and voltage translation between domains. Use Value: 180 V V_CBO prevents breakdown during transient coupling; robust ESD tolerance (per JEDEC JESD22-A114) enhances system reliability.

Gas Discharge Display Driver

High-Voltage Signal Amplifier

Use Scenario: Driving individual segments of neon or Nixie tube displays powered from 100–150 V DC supplies.

IC Role / Device Role / Timing Role: NPN switch controlling current flow through display cathodes/anodes with precise on/off timing.

Use Value: 160 V V_CEO ensures safe operation at display supply voltage; low V_CE(sat) minimizes power dissipation during active segment illumination.

Use Scenario: Amplifying sensor signals (e.g., piezoelectric transducers, photomultiplier outputs) referenced to high-voltage bias rails.

IC Role / Device Role / Timing Role: Linear NPN amplifier stage providing gain before ADC input or comparator threshold detection.

Use Value: 100 MHz f_T and 8.0 dB noise figure preserve signal integrity; wide h_FE range simplifies bias network design across production lots.

Relay Coil Driver

Industrial Interface Buffer

Use Scenario: Switching 24–48 V DC relays in PLC output modules or HVAC control panels.

IC Role / Device Role / Timing Role: Saturated switch delivering >500 mA coil current with minimal voltage drop and thermal rise.

Use Value: 600 mA I_C rating and 625 mW P_D support continuous relay actuation without derating; TO-92 form factor enables dense board layout.

Use Scenario: Level-shifting and isolating logic signals between microcontroller I/O and 12–24 V field buses (e.g., 4–20 mA transmitter interfaces).

IC Role / Device Role / Timing Role: Discrete transistor buffer providing galvanic separation and voltage translation between domains.

Use Value: 180 V V_CBO prevents breakdown during transient coupling; robust ESD tolerance (per JEDEC JESD22-A114) enhances system reliability.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N5550	Lower V_CEO (140 V) and reduced h_FE min (60 at I_C = 10 mA); otherwise identical TO-92 package and pinout.	Suitable only where supply voltage remains ≤120 V; less margin for surge transients or aging effects.	Select when cost sensitivity outweighs need for 160 V headroom and higher gain consistency.
MPSA42	Higher V_CEO (300 V), lower I_C (500 mA), and smaller h_FE range (40–120); same TO-92 footprint but different pinout (E-B-C).	Better for ultra-high-voltage flyback snubbers or vacuum tube heater drivers; not pin-compatible.	Choose for >200 V applications requiring enhanced breakdown safety, accepting trade-offs in gain and current capacity.

Compared with 2N5551TAR, 2N5550 offers lower cost but reduced voltage margin and gain stability, while MPSA42 provides superior voltage rating at the expense of current drive and pin compatibility - making 2N5551TAR optimal for balanced high-voltage switching and amplification where 160 V and 600 mA are simultaneously required.

Availability

2N5551TAR is available at Aetrix Electronics and suitable for gas discharge display drivers, high-voltage signal amplifiers, and relay coil drivers requiring stable component supply across industrial control, instrumentation, and legacy equipment repair programs.

Supply support for 2N5551TAR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2N5551TAR belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, originally developed by Fairchild Semiconductor and optimized for high-voltage amplification and switching in cost-sensitive, reliability-critical applications.

FAQ

What is the pin configuration of the 2N5551TAR?

The 2N5551TAR uses a TO-92 package with center-collector pinout: Pin 1 is Emitter, Pin 2 is Collector, and Pin 3 is Base. This configuration is confirmed in Fairchild's original datasheet Rev. 1.1.0 and maintained in ON Semiconductor's post-integration documentation. The 2N5551TAR pinout differs from EBC or ECB variants and must be verified before PCB layout.

Does the 2N5551TAR support switching applications?

Yes, the 2N5551TAR is widely used in switching applications including relay drivers and display segment control. Its 0.15 V V_CE(sat) at 10 mA and 600 mA I_C rating enable efficient saturation, while its 160 V V_CEO allows safe operation with inductive loads and flyback voltages up to 120 V. The 2N5551TAR is not intended for high-frequency PWM (>1 MHz) due to minority-carrier storage limitations.

What is the maximum operating temperature for the 2N5551TAR?

The 2N5551TAR has a maximum junction temperature (T_J) of +150 °C and a storage temperature range of –55 °C to +150 °C. At ambient temperatures above 25 °C, power dissipation must be linearly derated at 5.0 mW/°C. For continuous operation at 100 °C ambient, the 2N5551TAR supports ≤250 mW dissipation - verified in thermal characterization data from the original Fairchild datasheet.

How does the 2N5551TAR compare to the MMBT5551?

The 2N5551TAR is the through-hole TO-92 version, while MMBT5551 is the surface-mount SOT-23 variant. Both share identical electrical characteristics (V_CEO, h_FE, f_T), but differ in package thermal performance: 2N5551TAR has 625 mW P_D and 200 °C/W R_θJA, versus MMBT5551's 350 mW and 357 °C/W. The 2N5551TAR is preferred for higher-power or prototyping use; MMBT5551 suits space-constrained automated assembly.

Is the 2N5551TAR RoHS compliant?

Yes, the 2N5551TAR is RoHS compliant and meets lead-free soldering requirements per JEDEC J-STD-020. ON Semiconductor confirms compliance for all active 2N5551 variants, including 2N5551TAR, under exemption 7a (lead in high-melting-temperature type solders) where applicable. Full compliance documentation is available via ON Semiconductor's Quality & Environmental page.

2N5551TAR Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Packaging:: Tape & Box (TB)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 600 mA

Voltage - Collector Emitter Breakdown (Max):: 160 V

Vce Saturation (Max) @ Ib, Ic:: 200mV @ 5mA, 50mA

Current - Collector Cutoff (Max):: 50nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 80 @ 10mA, 5V

Power - Max:: 625 mW

Frequency - Transition:: 100MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

2N5551TAR FAQ

1.How can I place an order for 2N5551TAR through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N5551TAR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 2N5551TAR reliable?

The price and inventory of 2N5551TAR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N5551TAR is usually 5 days.

3.What payment methods are accepted for 2N5551TAR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N5551TAR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N5551TAR?

2N5551TAR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N5551TAR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 2N5551TAR?

For technical support, including 2N5551TAR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N5551TAR requirements.

6.How does Aetrix verify that 2N5551TAR is sourced from the original manufacturer or authorized distributors?

All 2N5551TAR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 2N5551TAR meets industry standards.

7.What is the process for return or replacement of 2N5551TAR?

All 2N5551TAR units undergo pre-shipment inspection (PSI). If there is an issue with 2N5551TAR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 2N5551TAR part is unused and in its original packaging.

Return procedure for 2N5551TAR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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