onsemi 2N3904_J18Z

Overview

2N3904_J18Z from ON Semiconductor is an NPN general-purpose bipolar junction transistor used for amplification and switching in low-power analog and digital circuits. It delivers DC current gain (hFE) of 70–300 at IC = 1.0 mA, VCE = 1.0 V; supports 100 MHz current gain–bandwidth product (fT); withstands 40 V collector-emitter voltage (VCEO); and operates across –55°C to +150°C junction temperature range. It is widely deployed in signal conditioning stages of sensor interfaces and discrete logic level translation.

For engineers reviewing the 2N3904_J18Z datasheet, pinout, applications, or equivalent options, key selection criteria include verified TO-92 package compatibility, confirmed hFE variation across IC = 0.1–100 mA, saturation voltage performance at IB/IC = 1/10 mA and 5/50 mA, thermal resistance (RθJA = 200°C/W), and noise figure (NF = 5.0 dB at 10 Hz–15.7 kHz).

Technical Context

The 2N3904_J18Z implements a planar epitaxial NPN structure optimized for high-speed switching and linear amplification. Its fT = 300 MHz enables RF front-end use up to VHF bands, while its low Cobo = 4.0 pF and Cibo = 8.0 pF minimize capacitive loading in high-impedance nodes.

It features defined saturation behavior with VCE(sat) ≤ 0.2 V at IC = 10 mA / IB = 1.0 mA and ≤ 0.3 V at IC = 50 mA / IB = 5.0 mA, supporting reliable on-state operation in discrete gate drivers and LED current switches. Base-emitter turn-on voltage (VBE(on)) ranges from 0.65 V to 0.95 V depending on operating point, enabling predictable bias network design.

Key Specifications

Pinout & Package

2N3904_J18Z is housed in a through-hole TO-92 3-lead package with standard EBC (Emitter–Base–Collector) pin configuration. The package provides mechanical robustness and solderability for prototyping and low-volume production.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT3904 and PZT3904, the 2N3904_J18Z offers optimal trade-off between through-hole manufacturability, thermal performance (625 mW PD), and proven reliability in legacy and new designs-making it preferred for prototyping, repair, and cost-sensitive volume production where TO-92 is acceptable.

Availability

2N3904_J18Z is available at Aetrix Electronics and suitable for audio preamplifiers, sensor interface modules, digital level translators, and discrete LED/relay drivers requiring stable component supply and long-term obsolescence management.

Supply support for 2N3904_J18Z 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 energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2N3904_J18Z belongs to ON Semiconductor's legacy general-purpose transistor product line, designed for broad compatibility, ease of use, and reliability in discrete amplifier and switching functions across educational, commercial, and industrial electronics.

FAQ

What is the maximum collector current rating for the 2N3904_J18Z?

The 2N3904_J18Z has a continuous collector current rating (IC) of 200 mA per Absolute Maximum Ratings. However, practical operation is limited by power dissipation: at TA = 25°C, its 625 mW total device dissipation allows ~150 mA in typical TO-92 mounting conditions before exceeding TJ = 150°C. Derating is required above 25°C at 5.0 mW/°C.

Does the 2N3904_J18Z support high-frequency amplification?

Yes, the 2N3904_J18Z delivers a current gain–bandwidth product (fT) of 300 MHz under standard test conditions (IC = 10 mA, VCE = 20 V). This enables effective small-signal amplification up to VHF frequencies in tuned or broadband configurations, provided layout parasitics and bias stability are controlled.

What is the pin configuration of the 2N3904_J18Z in the TO-92 package?

The 2N3904_J18Z uses the standard TO-92 EBC (Emitter–Base–Collector) pinout: when viewing the flat side with leads downward, left-to-right is E–B–C. This configuration is consistent across ON Semiconductor's 2N3904 variants and critical for correct orientation during PCB assembly and breadboarding.

How does the 2N3904_J18Z compare to the MMBT3904 in terms of thermal performance?

The 2N3904_J18Z (TO-92) has RθJA = 200°C/W, while the MMBT3904 (SOT-23) has RθJA = 357°C/W. This means the 2N3904_J18Z dissipates heat more effectively in still air, allowing ~1.8× higher continuous power (625 mW vs. 350 mW) before reaching thermal limits-making it preferable in thermally demanding discrete designs.

Can the 2N3904_J18Z be used in linear regulator pass transistor applications?

The 2N3904_J18Z is not recommended as a pass transistor in linear regulators due to its limited power dissipation (625 mW) and lack of built-in thermal protection. While it can source up to 200 mA, sustained operation near VCE × IC limits risks thermal runaway. Dedicated power transistors or integrated LDOs are safer and more efficient alternatives.