Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

onsemi 2N5551CTA

Name: 2N5551CTA
Brand: onsemi
SKU: 2N5551CTA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: 2N5551CTA

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: 2N5551CTA.pdf

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

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:2,593

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

2N5551CTA from ON Semiconductor is an NPN general-purpose amplifier transistor designed for high-voltage linear amplification and gas discharge display driver circuits. It features V_CEO = 160 V, I_C = 600 mA, h_FE = 80–250 (at I_C = 10 mA), f_T = 100 MHz, and TO-92 package with center-collector pinout (Emitter–Collector–Base). It is commonly used in low-frequency switching and analog gain stages in industrial control interfaces.

For engineers reviewing the 2N5551CTA datasheet, pinout, applications, or equivalent options, key selection criteria include its high V_CEO rating, wide h_FE range across operating currents, low V_CE(sat) at moderate drive levels, and thermal performance in TO-92 packages - all critical for reliable operation in HV bias networks and discrete amplifier designs.

Technical Context

This device operates as a silicon NPN bipolar junction transistor optimized for general-purpose amplification and medium-speed switching. Its design supports stable DC current gain up to 250 at I_C = 10 mA and retains usable gain (h_FE ≥ 30) even at I_C = 50 mA, enabling flexible biasing in Class-A and Class-AB stages.

Thermal behavior is defined by R_θJA = 200 °C/W (TO-92), PD = 625 mW at 25 °C with 5.0 mW/°C derating, and T_J(max) = 150 °C - making it suitable for ambient-temperature-stable applications without forced cooling in standard PCB layouts.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	160 V - Enables use in circuits with collector potentials up to 160 V relative to emitter, supporting HV analog stages and neon lamp drivers.
I_C (max)	600 mA - Supports moderate-power switching and amplification without external current limiting in non-saturated configurations.
h_FE	80–250 - Wide DC current gain range allows predictable bias design across production lots and temperature (25–125 °C).
f_T	100 MHz - Sufficient for audio amplification, low-speed digital switching (<10 MHz), and RF pre-driver applications up to VHF band edge.
V_CE(sat)	0.15 V @ I_C = 10 mA, I_B = 1 mA - Low saturation voltage reduces power loss and heat generation in switching mode.
P_D	625 mW @ 25 °C - Delivers usable power handling in TO-92 without heatsinking for intermittent or low-duty-cycle operation.

Pinout & Package

2N5551CTA uses the TO-92 3-lead molded plastic package with center-collector configuration (suffix "-C" per ordering table). Lead identification: Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Reference node for bias network; connects to ground or negative rail in common-emitter configurations.
2 (Collector)	High-voltage output terminal	Carries amplified output current; rated for 160 V standoff and 600 mA continuous conduction.
3 (Base)	Control input terminal	Accepts forward-biased current to modulate collector current; requires ~1.0 V V_BE(sat) at typical drive conditions.

Key Features

Feature	Design Value
High V_CEO rating	160 V enables direct interface with 100–150 V supply rails in display drivers and HV sensor signal conditioning.
Wide h_FE range	80–250 at I_C = 10 mA ensures consistent gain across manufacturing batches and simplifies bias resistor selection.
Low V_CE(sat)	0.15 V minimizes conduction loss in switching applications, improving efficiency in relay drivers and LED matrix controllers.
100 MHz f_T	Supports stable small-signal amplification up to 10 MHz and fast edge response in pulse amplifiers and waveform generators.
TO-92 center-collector layout	Standardized pinout (E-C-B) simplifies PCB layout reuse across Fairchild/ON Semi NPN amplifier families like 2N5401/2N5551.

Applications

Gas Discharge Display Driver	Analog Audio Pre-Amplifier
Use Scenario: Driving individual segments of neon or Nixie tubes requiring 90–150 V anode voltage and 1–5 mA segment current. IC Role / Device Role / Timing Role: High-voltage NPN switch controlling current path between HV anode and grounded cathode. Use Value: V_CEO = 160 V and I_C = 600 mA allow direct segment control without external HV transistors or level-shifting circuitry.	Use Scenario: First-stage voltage amplification in microphone preamps or instrument input buffers operating from ±12 V supplies. IC Role / Device Role / Timing Role: Common-emitter linear amplifier with emitter degeneration for stable gain and low distortion. Use Value: h_FE ≥ 80 at I_C = 1 mA and f_T = 100 MHz support clean 20 Hz–20 kHz response with <1% THD at 1 V_PP output.
Industrial Relay Interface	Low-Frequency Pulse Amplifier
Use Scenario: Isolating microcontroller GPIO outputs from 24–48 V DC relay coils with flyback protection. IC Role / Device Role / Timing Role: Medium-current saturated switch turning relay coil on/off with minimal base drive. Use Value: V_CE(sat) ≤ 0.20 V at I_C = 50 mA limits power dissipation to <10 mW, eliminating need for heatsink in PCB-mounted relays.	Use Scenario: Amplifying TTL/CMOS logic pulses (1–10 kHz) to drive 50 Ω coaxial lines or transformer-coupled loads. IC Role / Device Role / Timing Role: Emitter-follower buffer stage providing low-output-impedance drive with unity voltage gain. Use Value: C_obo = 6.0 pF and C_ibo = 20 pF minimize capacitive loading, preserving rise/fall times <35 ns at 10 V_PP.

Gas Discharge Display Driver

Analog Audio Pre-Amplifier

Use Scenario: Driving individual segments of neon or Nixie tubes requiring 90–150 V anode voltage and 1–5 mA segment current.

IC Role / Device Role / Timing Role: High-voltage NPN switch controlling current path between HV anode and grounded cathode.

Use Value: V_CEO = 160 V and I_C = 600 mA allow direct segment control without external HV transistors or level-shifting circuitry.

Use Scenario: First-stage voltage amplification in microphone preamps or instrument input buffers operating from ±12 V supplies.

IC Role / Device Role / Timing Role: Common-emitter linear amplifier with emitter degeneration for stable gain and low distortion.

Use Value: h_FE ≥ 80 at I_C = 1 mA and f_T = 100 MHz support clean 20 Hz–20 kHz response with <1% THD at 1 V_PP output.

Industrial Relay Interface

Low-Frequency Pulse Amplifier

Use Scenario: Isolating microcontroller GPIO outputs from 24–48 V DC relay coils with flyback protection.

IC Role / Device Role / Timing Role: Medium-current saturated switch turning relay coil on/off with minimal base drive.

Use Value: V_CE(sat) ≤ 0.20 V at I_C = 50 mA limits power dissipation to <10 mW, eliminating need for heatsink in PCB-mounted relays.

Use Scenario: Amplifying TTL/CMOS logic pulses (1–10 kHz) to drive 50 Ω coaxial lines or transformer-coupled loads.

IC Role / Device Role / Timing Role: Emitter-follower buffer stage providing low-output-impedance drive with unity voltage gain.

Use Value: C_obo = 6.0 pF and C_ibo = 20 pF minimize capacitive loading, preserving rise/fall times <35 ns at 10 V_PP.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N5551TA	Same die, identical electrical specs, but TO-92 with standard E-B-C pinout (not center-collector).	Requires PCB layout revision due to pin 2/base vs. pin 2/collector mapping mismatch.	Select only if existing board uses E-B-C orientation and center-collector mechanical constraints are not required.
MPSA42	V_CEO = 300 V, h_FE = 40–200, TO-92 package, same pinout (E-C-B) as 2N5551CTA.	Higher voltage rating suits >200 V applications (e.g., CRT anode regulation), but lower h_FE reduces gain margin at low I_C.	Preferred when system voltage exceeds 160 V; verify h_FE stability at target I_C before substitution.

Compared with 2N5551TA and MPSA42, the 2N5551CTA offers optimal balance of high-voltage capability, gain consistency, and standardized center-collector layout - making it ideal for legacy display driver designs where pin compatibility and proven reliability are prioritized over extended voltage headroom.

Availability

2N5551CTA is available at Aetrix Electronics and suitable for gas discharge display drivers, analog audio pre-amplifiers, and industrial relay interfaces requiring stable component supply and long-term manufacturability.

Supply support for 2N5551CTA 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 power management, analog, sensors, and discrete devices, with roots in Fairchild Semiconductor's legacy product lines.

The 2N5551CTA belongs to ON Semiconductor's general-purpose bipolar transistor family, engineered for robustness in industrial and display applications where high-voltage tolerance and DC gain stability are essential.

FAQ

What is the pin configuration of the 2N5551CTA?

The 2N5551CTA uses a TO-92 package with center-collector pinout: Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base. This "-C" suffix explicitly denotes the center-collector arrangement, distinguishing it from standard E-B-C variants like 2N5551TA. The configuration is confirmed in Fairchild's ordering information table and physical dimension diagrams.

Does the 2N5551CTA support high-frequency signal amplification?

Yes, the 2N5551CTA has an f_T of 100 MHz, enabling effective small-signal amplification up to approximately 10 MHz with stable gain. Its C_obo = 6.0 pF and C_ibo = 20 pF limit parasitic loading, supporting clean pulse response in waveform shaping and RF pre-driver roles - though it is not intended for GHz-range RF front-ends.

What is the maximum continuous collector current for the 2N5551CTA?

The 2N5551CTA supports a maximum continuous collector current (I_C) of 600 mA at T_A = 25 °C. Derating applies above 25 °C (5.0 mW/°C), and actual usable current depends on PCB thermal design and ambient conditions. At 75 °C ambient, maximum I_C drops to ~450 mA assuming no heatsink.

How does the h_FE of the 2N5551CTA vary with operating conditions?

The 2N5551CTA exhibits h_FE = 80–250 at I_C = 10 mA and V_CE = 5 V, dropping to ≥30 at I_C = 50 mA. Gain decreases with rising temperature and falls below 80 below I_C = 1 mA. Designers should reference Figure 8 in the datasheet for h_FE vs. I_C curves across −40 °C to 125 °C to ensure stable bias in the 2N5551CTA.

Is the 2N5551CTA suitable for life support or medical applications?

No, the 2N5551CTA is not authorized for use in life support systems, FDA Class 3 medical devices, or implantable applications. ON Semiconductor explicitly excludes such uses in its product disclaimer. For medical-grade alternatives, consult ON Semiconductor's certified automotive or industrial functional-safety portfolios - the 2N5551CTA remains intended for industrial, display, and general-purpose amplifier use only.

2N5551CTA 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

2N5551CTA FAQ

1.How can I place an order for 2N5551CTA through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N5551CTA 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 2N5551CTA reliable?

The price and inventory of 2N5551CTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N5551CTA is usually 5 days.

3.What payment methods are accepted for 2N5551CTA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N5551CTA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N5551CTA?

2N5551CTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N5551CTA 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 2N5551CTA?

For technical support, including 2N5551CTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N5551CTA requirements.

6.How does Aetrix verify that 2N5551CTA is sourced from the original manufacturer or authorized distributors?

All 2N5551CTA 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 2N5551CTA meets industry standards.

7.What is the process for return or replacement of 2N5551CTA?

All 2N5551CTA units undergo pre-shipment inspection (PSI). If there is an issue with 2N5551CTA, 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 2N5551CTA part is unused and in its original packaging.

Return procedure for 2N5551CTA:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…