onsemi 2N3904_J25Z

Overview

2N3904_J25Z from ON Semiconductor is an NPN general-purpose bipolar junction transistor (BJT) designed for amplification and switching in low-power analog and digital circuits. It delivers DC current gain (h_FE) of 70–300 at I_C = 1.0 mA, V_CE = 1.0 V; supports 100 MHz current gain–bandwidth product (f_T); withstands 40 V collector-emitter breakdown voltage (V_CEO); and operates across –55 °C to +150 °C. It is widely used in signal conditioning stages of sensor interfaces and discrete logic level translators.

For engineers reviewing the 2N3904_J25Z datasheet, pinout, applications, or equivalent options, this page provides verified package mapping (TO-92), confirmed absolute maximum ratings, validated switching timing (t_d = 35 ns, t_s = 200 ns), real-world thermal resistance (R_θJA = 200 °C/W), and two field-validated alternative parts with documented parameter deviations.

Technical Context

The 2N3904_J25Z implements a planar epitaxial NPN structure optimized for high-speed switching and linear amplification. Its f_T = 300 MHz enables stable operation up to VHF band in RF preamplifier stages, while its low C_obo = 4.0 pF and C_ibo = 8.0 pF minimize capacitive loading in high-impedance node applications.

It features V_CE(sat) = 0.2 V at I_C = 10 mA / I_B = 1.0 mA and V_BE(sat) = 0.65–0.85 V under same conditions-enabling efficient saturation in TTL-compatible digital drivers. Its noise figure of 5.0 dB at I_C = 100 μA makes it suitable for low-level audio and instrumentation front-ends.

Key Specifications

Pinout & Package

2N3904_J25Z is housed in a through-hole TO-92 package (JEDEC TO-92 variant), with standard E-B-C pinout when viewed from flat side with leads down: Emitter (pin 1), Base (pin 2), Collector (pin 3). The package supports manual soldering and wave soldering per IPC-J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT3904 and BC547B, the 2N3904_J25Z offers superior thermal performance (625 mW PD, R_θJA = 200 °C/W) and guaranteed E-B-C pinout-making it optimal for through-hole prototyping, high-reliability industrial controls, and applications needing margin above 150 mW dissipation.

Availability

2N3904_J25Z is available at Aetrix Electronics and suitable for industrial control panels, sensor interface modules, and educational electronics kits requiring stable component supply and long-term obsolescence management.

Supply support for 2N3904_J25Z 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_J25Z belongs to ON Semiconductor's legacy general-purpose transistor product line, originally developed by Fairchild and maintained for broad compatibility in discrete amplifier and switching designs across decades of electronics development.

FAQ

What is the maximum collector current rating for the 2N3904_J25Z?

The 2N3904_J25Z has an absolute maximum continuous collector current (I_C) of 200 mA at T_A = 25 °C. Derating applies above 25 °C per the specified 5.0 mW/°C thermal slope. For sustained operation near this limit, PCB copper area and ambient airflow must be validated to keep junction temperature below 150 °C. The 2N3904_J25Z achieves full specification compliance only within this thermal boundary.

Does the 2N3904_J25Z support high-frequency amplification?

Yes-the 2N3904_J25Z delivers a current gain–bandwidth product (f_T) of 300 MHz under standard test conditions (I_C = 10 mA, V_CE = 20 V). This enables usable small-signal gain in common-emitter configurations up to approximately 30 MHz, provided layout minimizes stray capacitance and grounding is optimized. The 2N3904_J25Z is routinely applied in VHF preamplifiers and RF detector stages where cost and simplicity outweigh integrated alternatives.

What is the pin configuration of the 2N3904_J25Z in TO-92 package?

The 2N3904_J25Z uses the standard JEDEC TO-92 pinout: when viewing the flat side of the package with leads pointing downward, the leftmost pin is Emitter (pin 1), center pin is Base (pin 2), and rightmost pin is Collector (pin 3). This E-B-C arrangement is confirmed in Fairchild/ON Semiconductor documentation and matches industry-standard 2N3904 variants. The 2N3904_J25Z must be mounted with correct orientation to avoid circuit malfunction.

How does the 2N3904_J25Z compare to the MMBT3904 in terms of thermal performance?

The 2N3904_J25Z (TO-92) has R_θJA = 200 °C/W and P_D = 625 mW, whereas the MMBT3904 (SOT-23) has R_θJA = 357 °C/W and P_D = 350 mW. This means the 2N3904_J25Z can dissipate nearly twice the power under identical ambient conditions. In practice, the 2N3904_J25Z sustains 100 mW with only ~20 °C junction rise, while the MMBT3904 reaches the same rise at just 56 mW. The 2N3904_J25Z remains preferred for thermally demanding through-hole applications.

Is the 2N3904_J25Z suitable for low-noise audio applications?

Yes-the 2N3904_J25Z specifies a noise figure (NF) of 5.0 dB at I_C = 100 μA, V_CE = 5.0 V, R_S = 1.0 kΩ, and 10 Hz–15.7 kHz bandwidth. This performance is validated in electret microphone preamplifier designs and low-level sensor amplifiers. Optimal noise performance requires careful attention to base bias network impedance and shielding; the 2N3904_J25Z delivers repeatable results when operated within its specified low-current, low-voltage noise region.