onsemi 2N5551CBU

Overview

2N5551CBU from ON Semiconductor (formerly Fairchild) is an NPN general-purpose amplifier optimized for high-voltage linear amplification and gas discharge display driver circuits. It delivers V_CEO = 160 V, I_C = 600 mA continuous, h_FE = 80–250 at I_C = 10 mA/V_CE = 5 V, and f_T = 100 MHz - enabling robust operation in medium-speed switching and analog gain stages.

For engineers reviewing the 2N5551CBU datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92 package thermal resistance (R_θJA = 200 °C/W), low V_CE(sat) = 0.15 V at I_C = 10 mA/I_B = 1 mA, and ESD-tolerant emitter-base breakdown (V_EBR = 6 V), critical for industrial interface and pulse amplification designs.

Technical Context

The 2N5551CBU operates as a discrete silicon NPN bipolar junction transistor with fixed lead configuration (Emitter–Collector–Base, pin 1–2–3). Its design emphasizes high-voltage tolerance and stable DC current gain across temperature, supported by guaranteed h_FE minima at multiple I_C points (80 @ 1 mA, 80 @ 10 mA, 30 @ 50 mA).

Thermal performance is defined by P_D = 625 mW at T_A = 25 °C with 5.0 mW/°C derating, and junction temperature range of –55 °C to +150 °C. Small-signal behavior includes C_obo = 6.0 pF and C_ibo = 20 pF at specified bias conditions, supporting predictable RF impedance matching up to 100 MHz.

Key Specifications

Pinout & Package

2N5551CBU uses the standard TO-92 3-lead molded plastic package with center-collector pinout (suffix "C" per ordering table): Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base. The package meets JEDEC TO-92 compliance and supports through-hole mounting with 0.200" lead spacing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2N5551CBU, 2N5550BU trades 20 V breakdown margin for minor cost reduction, while MPSA42 extends voltage capability at the expense of saturation efficiency - making 2N5551CBU optimal for balanced high-voltage, medium-current, low-loss applications.

Availability

2N5551CBU is available at Aetrix Electronics and suitable for gas discharge display drivers, high-voltage linear amplifiers, relay interface circuits, and pulse generator output stages requiring stable component supply and long-term industrial availability.

Supply support for 2N5551CBU 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 (formerly Fairchild Semiconductor) is a global leader in energy-efficient semiconductor solutions, specializing in power management, analog, sensors, and discrete devices for automotive, industrial, and consumer markets.

The 2N5551CBU belongs to ON Semiconductor's legacy general-purpose transistor product line, designed specifically for cost-sensitive, high-reliability linear and switching applications in industrial controls, displays, and interface circuitry.

FAQ

What is the pin configuration of the 2N5551CBU?

The 2N5551CBU 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 the Fairchild/ON Semiconductor datasheet Rev. 1.1.0 and matches the "-C" suffix designation meaning "Center Collector." The 2N5551CBU pinout is not interchangeable with base-center variants like 2N5551TA.

Does the 2N5551CBU support high-frequency amplification?

Yes, the 2N5551CBU has a current-gain bandwidth product (f_T) of 100 MHz under standard test conditions (I_C = 10 mA, V_CE = 10 V), enabling effective small-signal amplification up to the upper audio band and low-MHz digital signal conditioning. However, gain rolls off above 10 MHz in practical common-emitter configurations due to parasitic capacitances (C_obo = 6.0 pF, C_ibo = 20 pF).

What is the maximum power dissipation of the 2N5551CBU at room temperature?

The 2N5551CBU has a total device dissipation (P_D) of 625 mW at ambient temperature (T_A) = 25 °C. This value decreases linearly at 5.0 mW/°C above 25 °C, reaching zero at T_A = 150 °C. Actual safe operating power depends on PCB layout, airflow, and thermal interface - the 2N5551CBU requires careful thermal design above ~300 mW continuous dissipation.

Can the 2N5551CBU replace the 2N2222 in high-voltage circuits?

The 2N5551CBU can replace the 2N2222 in high-voltage circuits where V_CEO > 40 V is required, as it offers 160 V versus 2N2222's 40 V rating. However, the 2N5551CBU has lower h_FE at low currents (<80 @ 1 mA vs. 2N2222's >100) and higher V_CE(sat). For 2N5551CBU substitution, verify bias networks and ensure collector voltage does not exceed 160 V - the 2N5551CBU is not a drop-in replacement but a functional upgrade for voltage-critical roles.

Is the 2N5551CBU suitable for automotive applications?

The 2N5551CBU is qualified for operation from –55 °C to +150 °C junction temperature and is widely used in under-hood and industrial control applications. While not AEC-Q101 qualified, its thermal and voltage specs meet many non-safety-critical automotive subsystem requirements (e.g., HVAC actuators, lighting interfaces). For 2N5551CBU deployment in automotive contexts, full system-level validation including board-level thermal cycling and EMC testing is required per OEM specifications.