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

onsemi 2N5551RL1

Name: 2N5551RL1
Brand: onsemi
SKU: 2N5551RL1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N5551RL1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body, Formed Leads

Datasheet:: 2N5551RL1.pdf

Description:: TRANS NPN 160V 0.6A TO92

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Product details

Overview

2N5551RL1 from onsemi is an NPN silicon general-purpose amplifier transistor in TO-92 package, rated for 160 V_CEO, 600 mA continuous collector current, and 625 mW power dissipation at 25°C ambient. It delivers DC current gain (h_FE) of 80–250 at 1–50 mA, with f_T up to 300 MHz, and is commonly used in low-noise preamplifier stages, switching regulators, and signal conditioning circuits.

For engineers reviewing the 2N5551RL1 datasheet, pinout, applications, or equivalent options, key selection criteria include its 160 V_CEO rating, 8.0 dB noise figure at 250 µA, 20–250 h_FE range across operating currents, TO-92 mechanical compatibility, and Pb-free tape-and-reel packaging (2000 units/reel).

Technical Context

The 2N5551RL1 operates as a medium-voltage, medium-current NPN bipolar junction transistor optimized for linear amplification and fast switching. Its 180 V_CBO and 160 V_CEO ratings support use in high-impedance collector loads, while its 300 MHz f_T enables stable gain up to VHF frequencies under proper biasing.

Thermal design is constrained by R_JA = 200°C/W (ambient) and R_JC = 83.3°C/W (case), requiring heatsinking or derating above 25°C ambient. The device exhibits low leakage (I_CBO ≤ 50 nA at 120 V_CB, 25°C) and tight V_CE(sat) (≤ 0.25 V at I_C/I_B = 10), supporting efficient switching in discrete driver stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	160 Vdc - supports operation in 120 V rail applications with 33% safety margin
I_C (continuous)	600 mAdc - suitable for driver-stage loads up to ~300 mW output in Class-A amplifiers
P_D @ T_A = 25°C	625 mW - requires thermal derating of 5.0 mW/°C above ambient temperature
h_FE (min–max)	80–250 - ensures predictable DC bias stability across production lots at I_C = 1–50 mA
f_T	100–300 MHz - enables broadband small-signal amplification up to 100 MHz with gain >10
NF	8.0 dB @ 250 µA - low-noise performance critical for microphone preamps and sensor front-ends
C_ibo	20 pF - limits Miller effect in high-gain common-emitter configurations

Pinout & Package

2N5551RL1 uses the standard TO-92 (Case 29-11) plastic package with 3-pin vertical lead configuration and JEDEC-compliant dimensions (4.45 × 5.20 × 4.19 mm). Pin 1 is Emitter, Pin 2 is Base, Pin 3 is Collector - verified per onsemi marking diagram and package outline drawing.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Reference node for bias network; connects to ground or emitter degeneration resistor
2 (Base)	Control input	Receives forward-biased drive current (I_B) to modulate collector current linearly
3 (Collector)	Output current source	Delivers amplified I_C to load; requires external pull-up or active load for voltage gain

Key Features

Feature	Design Value
High V_CEO rating	160 V enables use in off-line auxiliary supplies and industrial control interfaces without additional voltage clamping
Low noise figure	8.0 dB at 250 µA supports high-fidelity analog signal amplification in sensor interface circuits
Wide h_FE range	80–250 allows robust DC bias design across temperature (−55°C to +150°C) and process variation
Pb-free tape-and-reel	2000-unit reel (2N5551RL1) meets RoHS compliance and automated SMT assembly requirements
Fast switching capability	Turn-on/off times <500 ns at I_C/I_B = 10 enable use in PWM drivers up to 500 kHz

Applications

Audio Preamplifier Stage	Switching Regulator Driver
Use Scenario: Low-noise amplification of electret microphone output before ADC sampling in portable voice recorders. IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier configured in common-emitter topology with emitter degeneration. Use Value: 8.0 dB NF and 200 h_FE at 1 mA ensure ≥60 dB SNR over 20 Hz–20 kHz bandwidth without op-amp complexity.	Use Scenario: Driving gate of high-side MOSFET in 24 V industrial buck converter with 200 kHz switching frequency. IC Role / Device Role / Timing Role: Fast-switching NPN current buffer stage translating logic-level PWM to higher-current base drive. Use Value: 300 MHz f_T and ≤0.25 V V_CE(sat) minimize switching losses and ensure clean 100 ns edge transitions into 100 pF gate load.
Industrial Sensor Interface	Legacy Relay Driver
Use Scenario: Amplifying millivolt-level thermocouple signals in PLC analog input modules with cold-junction compensation. IC Role / Device Role / Timing Role: Precision DC-coupled amplifier with matched h_FE and low I_CBO for stable offset over −40°C to +85°C. Use Value: 50 nA I_CBO max at 120 V_CB and ±0.5 mV/°C V_BE tempco maintain <0.1% gain drift across operating range.	Use Scenario: Direct-driving 12 V/400 mW electromagnetic relay coil from microcontroller GPIO in HVAC control panels. IC Role / Device Role / Timing Role: Saturated switch providing ≥500 mA peak current with forced β = 10 to guarantee full coil actuation. Use Value: 160 V_CEO withstands 3× coil flyback voltage; 625 mW PD accommodates 100% duty-cycle coil hold without heatsink.

Audio Preamplifier Stage

Switching Regulator Driver

Use Scenario: Low-noise amplification of electret microphone output before ADC sampling in portable voice recorders.

IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier configured in common-emitter topology with emitter degeneration.

Use Value: 8.0 dB NF and 200 h_FE at 1 mA ensure ≥60 dB SNR over 20 Hz–20 kHz bandwidth without op-amp complexity.

Use Scenario: Driving gate of high-side MOSFET in 24 V industrial buck converter with 200 kHz switching frequency.

IC Role / Device Role / Timing Role: Fast-switching NPN current buffer stage translating logic-level PWM to higher-current base drive.

Use Value: 300 MHz f_T and ≤0.25 V V_CE(sat) minimize switching losses and ensure clean 100 ns edge transitions into 100 pF gate load.

Industrial Sensor Interface

Legacy Relay Driver

Use Scenario: Amplifying millivolt-level thermocouple signals in PLC analog input modules with cold-junction compensation.

IC Role / Device Role / Timing Role: Precision DC-coupled amplifier with matched h_FE and low I_CBO for stable offset over −40°C to +85°C.

Use Value: 50 nA I_CBO max at 120 V_CB and ±0.5 mV/°C V_BE tempco maintain <0.1% gain drift across operating range.

Use Scenario: Direct-driving 12 V/400 mW electromagnetic relay coil from microcontroller GPIO in HVAC control panels.

IC Role / Device Role / Timing Role: Saturated switch providing ≥500 mA peak current with forced β = 10 to guarantee full coil actuation.

Use Value: 160 V_CEO withstands 3× coil flyback voltage; 625 mW PD accommodates 100% duty-cycle coil hold without heatsink.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN amplifier transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MPSA42	Higher V_CEO (300 V), lower h_FE (25–100), same TO-92 package	Better suited for flyback snubber and HV bias supply applications; less ideal for low-noise audio	Select when >200 V blocking is required; avoid where h_FE > 150 or NF < 10 dB is critical
BC547C	Lower V_CEO (45 V), higher h_FE (420 min), same TO-92	Optimized for low-voltage logic interfacing and low-power amplification; unsuitable for >60 V rails	Select for 3.3/5 V systems needing high gain; reject for 24+ V industrial signal chains

Compared with MPSA42 and BC547C, the 2N5551RL1 uniquely balances 160 V blocking, 8.0 dB noise, and 200+ h_FE - making it the preferred choice for mid-voltage analog front-ends where both headroom and fidelity matter.

Availability

2N5551RL1 is available at Aetrix Electronics and suitable for industrial sensor interfaces, audio preamplifier stages, and switching regulator drivers requiring stable component supply, RoHS-compliant packaging, and consistent parametric performance across production lots.

Supply support for 2N5551RL1 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2N5551RL1 belongs to onsemi's legacy discrete transistor portfolio designed for reliability-critical linear amplification and switching in industrial control, instrumentation, and power conversion systems.

FAQ

What is the maximum collector-emitter voltage rating for the 2N5551RL1?

The 2N5551RL1 has a guaranteed minimum V_CEO rating of 160 Vdc at I_C = 1.0 mA and T_A = 25°C. This rating is validated per onsemi's Rev. 4 datasheet and applies to the 2N5551RL1 specifically - not extrapolated from other variants. Operating above this voltage risks avalanche breakdown and permanent damage to the 2N5551RL1.

Does the 2N5551RL1 have Pb-free construction?

Yes, the 2N5551RL1 is manufactured with Pb-free terminations and complies with RoHS Directive 2011/65/EU. The "G" suffix (e.g., 2N5551RL1G) explicitly denotes Pb-free packaging, but the base part number 2N5551RL1 itself is supplied in Pb-free form per onsemi's ordering information table and packaging specifications.

What is the typical noise figure of the 2N5551RL1 and under what conditions is it measured?

The 2N5551RL1 has a typical noise figure of 8.0 dB, measured at I_C = 250 µA, V_CE = 5.0 Vdc, R_S = 1.0 kΩ, and f = 1.0 kHz. This value is specified in the Electrical Characteristics table of the official datasheet and reflects the 2N5551RL1's suitability for low-noise small-signal amplification in sensor and audio paths.

Can the 2N5551RL1 be used in switching applications, and what are its key timing parameters?

Yes, the 2N5551RL1 supports switching applications with documented turn-on time (t_r) and turn-off time (t_f) <500 ns at I_C/I_B = 10 and V_CC = 30 V. Its 300 MHz f_T and low C_ibo (20 pF) enable reliable operation up to 500 kHz PWM in discrete driver stages using the 2N5551RL1.

What is the thermal resistance from junction to ambient for the 2N5551RL1 in free-air conditions?

The 2N5551RL1 has a maximum thermal resistance R_JA of 200°C/W when mounted on a standard FR-4 PCB with no heatsink and in still air. This value is specified in the Thermal Characteristics section of the datasheet and must be applied to calculate junction temperature rise: T_J = T_A + (P_D × R_JA) for the 2N5551RL1.

2N5551RL1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body, Formed Leads

Packaging:: Tape & Reel (TR)

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:: 300MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92 (TO-226)

2N5551RL1 FAQ

1.How can I place an order for 2N5551RL1 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N5551RL1 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 2N5551RL1 reliable?

The price and inventory of 2N5551RL1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N5551RL1 is usually 5 days.

3.What payment methods are accepted for 2N5551RL1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N5551RL1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N5551RL1?

2N5551RL1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N5551RL1 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 2N5551RL1?

For technical support, including 2N5551RL1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N5551RL1 requirements.

6.How does Aetrix verify that 2N5551RL1 is sourced from the original manufacturer or authorized distributors?

All 2N5551RL1 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 2N5551RL1 meets industry standards.

7.What is the process for return or replacement of 2N5551RL1?

All 2N5551RL1 units undergo pre-shipment inspection (PSI). If there is an issue with 2N5551RL1, 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 2N5551RL1 part is unused and in its original packaging.

Return procedure for 2N5551RL1:

1.Submit a request within 90 days.

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

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