onsemi 2N3442

Overview

2N3442 from onsemi is an NPN silicon power transistor designed for high-power industrial switching and linear amplification, with V_CEO(sus) = 140 Vdc (min), I_C = 10 Adc continuous, P_D = 117 W at T_C = 25°C, and R_JC = 1.17°C/W - deployed in high-fidelity audio output stages, series voltage regulators, and DC power switches.

For engineers reviewing the 2N3442 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical ratings, TO-204 (TO-3) mechanical interface details, second-breakdown-safe SOA curves, h_FE vs. temperature behavior, and validated alternatives for industrial power transistor replacement.

Technical Context

The 2N3442 operates as a high-current, high-voltage NPN bipolar junction transistor optimized for rugged industrial use. Its sustaining voltage rating (V_CEO(sus) = 140 Vdc) and excellent second breakdown capability enable reliable operation under transient overloads in linear and switching modes.

Thermal design is anchored by R_JC = 1.17°C/W and a maximum junction temperature of +200°C, supporting stable performance in high-ambient environments. Dynamic gain-bandwidth product f_T = 80 kHz at I_C = 2.0 Adc confirms suitability for audio-frequency and DC-controlled power applications-not RF or high-speed switching.

Key Specifications

Pinout & Package

2N3442 is housed in a hermetically sealed TO-204 (TO-3) metal package with collector-connected case. The standard pin configuration (Style 1) assigns Pin 1 to Base and Pin 2 to Emitter; the metal case serves as the Collector terminal.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJE13009 and 2N3055, the 2N3442 uniquely balances 140 V blocking, 117 W dissipation, and TO-3 thermal reliability - making it the preferred choice for industrial linear regulators and audio amplifiers operating above 80 V DC rails.

Availability

2N3442 is available at Aetrix Electronics and suitable for high-fidelity audio amplifier output stages, linear series voltage regulators, and industrial DC power switches requiring stable component supply, long-term lifecycle support, and traceable Pb-free sourcing options.

Supply support for 2N3442 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, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The 2N3442 belongs to onsemi's legacy high-power bipolar transistor family, engineered for ruggedized industrial linear and switching applications where thermal stability, second-breakdown immunity, and high-voltage sustain capability are critical.

FAQ

What is the maximum continuous collector current for the 2N3442?

The 2N3442 has a maximum continuous collector current (I_C) of 10 Adc at T_C = 25°C. This rating decreases with rising case temperature per the 0.67 W/°C derating curve. At T_C = 100°C, the usable I_C drops to approximately 5.5 Adc to maintain safe junction temperature. Always consult Figure 1 (Power Derating) and Figure 2 (SOA) in the official 2N3442 datasheet for thermal design validation.

Does the 2N3442 have a Pb-free version, and how does it differ?

Yes, the 2N3442G is the Pb-free variant of the 2N3442, fully compliant with RoHS Directive 2011/65/EU. It uses identical TO-204 (TO-3) packaging and maintains identical electrical and thermal specifications - including V_CEO(sus) = 140 Vdc, P_D = 117 W, and R_JC = 1.17°C/W. No layout or thermal redesign is needed when substituting 2N3442G for 2N3442 in new production.

What is the safe operating area (SOA) limitation for single-pulse operation of the 2N3442?

Per Figure 2 in the 2N3442 datasheet, the single-pulse SOA limit at T_J(pk) = 200°C allows simultaneous operation up to V_CE = 100 V and I_C = 10 A for pulse widths ≤1 ms. At longer durations (e.g., 100 ms), the boundary contracts to ~V_CE = 40 V / I_C = 10 A. This SOA envelope must be respected in linear-mode applications like audio amplifiers or regulators to prevent second breakdown.

How does the DC current gain (h_FE) of the 2N3442 vary with collector current and temperature?

The 2N3442 exhibits h_FE = 20–70 at I_C = 3.0 Adc and 7.5–70 at I_C = 10 Adc (V_CE = 4.0 Vdc, T_J = 25°C). Gain declines significantly at high current and elevated temperature - e.g., h_FE drops to ~12 at I_C = 10 A and T_J = 150°C (Figure 3). Base drive circuits must be designed for worst-case β to ensure saturation under all operating conditions.

Can the 2N3442 be used in switching power supplies operating above 20 kHz?

No - the 2N3442 is not suitable for high-frequency switching power supplies. Its f_T = 80 kHz and relatively slow turn-on/turn-off characteristics (not specified in provided data but implied by construction) make it appropriate only for audio-frequency amplification and low-frequency (<1 kHz) switching applications. For >20 kHz operation, MOSFETs or RF-optimized BJTs with f_T > 1 MHz should be selected instead of the 2N3442.