onsemi 2N5551G

Overview

2N5551G from onsemi is an NPN silicon general-purpose amplifier transistor in TO-92 package, rated for 160 V_CEO, 180 V_CBO, 600 mA continuous collector current, and 625 mW power dissipation at T_A = 25°C. It delivers DC current gain (h_FE) of 80–250 at I_C = 1.0–50 mA and supports high-frequency amplification up to 300 MHz f_T, commonly used in low-noise preamplifier stages and switching circuits.

For engineers reviewing the 2N5551G datasheet, pinout, applications, or equivalent options, key selection factors include its 160 V_CEO rating, 8.0 dB noise figure at 250 µA, 6.0 pF C_obo, TO-92 mechanical compatibility, and Pb-free compliance-critical for industrial signal conditioning and legacy replacement designs.

Technical Context

The 2N5551G operates as a medium-voltage, medium-current NPN bipolar junction transistor optimized for linear amplification and fast switching. Its h_FE range spans 80–250 across I_C = 1–50 mA, with V_CE(sat) ≤ 0.25 V at I_C/I_B = 10 and V_BE(sat) ≤ 1.2 V under same conditions.

It exhibits f_T = 100–300 MHz, C_ibo = 20 pF, C_obo = 6.0 pF, and NF = 8.0 dB at I_C = 250 µA, V_CE = 5 V, R_S = 1 kΩ, f = 1 kHz-enabling stable small-signal gain in RF front-ends and audio preamps where low capacitance and controlled noise are essential.

Key Specifications

Pinout & Package

2N5551G uses the standard TO-92 (Case 29-11) plastic package with straight or bent leads, 5.20 mm max height, and 2.66 mm max body width. Pin 1 is Emitter, Pin 2 is Base, Pin 3 is Collector - verified per onsemi marking diagram and package outline drawing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2N5551G, 2N5550G offers reduced voltage headroom but identical footprint and drive strength, while MPSA42 provides superior breakdown ratings at the cost of higher noise and lower DC gain-making 2N5551G the balanced choice for general-purpose 160 V, low-noise amplification.

Availability

2N5551G is available at Aetrix Electronics and suitable for industrial control interfaces, audio signal conditioning, RF intermediate frequency amplification, and relay driver circuits requiring stable component supply across long-lifecycle embedded programs.

Supply support for 2N5551G 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 focused on energy-efficient innovation for automotive, industrial, cloud, and intelligent edge applications.

The 2N5551G belongs to onsemi's legacy discrete transistor product line, designed specifically for robust, cost-effective general-purpose amplification and switching in industrial and consumer electronics.

FAQ

What is the maximum collector-emitter voltage rating for the 2N5551G?

The 2N5551G has a maximum collector-emitter voltage (V_CEO) rating of 160 Vdc, validated per onsemi's electrical characteristics table at I_C = 1.0 mA and T_A = 25°C. This rating ensures safe operation in 120 VAC-derived supplies with transient margin, and must be derated per thermal conditions in actual layout.

Does the 2N5551G have Pb-free construction?

Yes, the 2N5551G is explicitly marked as Pb-free in onsemi's ordering information and package description. It complies with RoHS Directive 2011/65/EU and is qualified for lead-free reflow soldering per JEDEC J-STD-020, with no lead content in die attach, bond wires, or external terminations.

What is the typical noise figure of the 2N5551G and under what conditions is it measured?

The 2N5551G has a noise figure (NF) 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 per onsemi's Electrical Characteristics table. This value reflects its suitability for low-noise preamplifier applications where signal integrity at microvolt levels is critical.

Can the 2N5551G replace the 2N2222A in existing designs?

The 2N5551G is not a direct drop-in replacement for the 2N2222A due to differences in V_CEO (160 V vs. 40 V), h_FE distribution, and f_T (300 MHz vs. ~250 MHz). While both are TO-92 NPN transistors, substituting 2N5551G into a 2N2222A design requires verification of bias stability, gain margin, and thermal limits-especially in low-voltage, high-current scenarios.

What is the thermal resistance junction-to-ambient (R_JA) for the 2N5551G in free-air conditions?

The 2N5551G has a thermal resistance junction-to-ambient (R_JA) of 200 °C/W when mounted on a standard PCB with no heatsink, per onsemi's Thermal Characteristics table. This value assumes minimal copper area; actual R_JA improves significantly with added copper pour or thermal vias, and must be factored into power dissipation calculations at elevated ambient temperatures.