onsemi 2N3904CTA

Overview

2N3904CTA 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, supports 100 MHz current gain–bandwidth product (f_T), withstands 40 V 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 translation.

For engineers reviewing the 2N3904CTA datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO/V_CBO ratings, h_FE variation across collector current, thermal resistance (R_θJA = 200°C/W), and TO-92 package compatibility with manual assembly and through-hole prototyping.

Technical Context

The 2N3904CTA implements a planar epitaxial NPN structure optimized for high-speed switching (t_d = 35 ns, t_s = 200 ns) and low-noise amplification (NF = 5.0 dB at 10 Hz–15.7 kHz). Its base-emitter saturation voltage (V_BE(sat) = 0.65–0.85 V at I_C = 10 mA) and collector-emitter saturation voltage (V_CE(sat) = 0.2 V) enable efficient operation in saturated-switch configurations.

Thermal design relies on its TO-92 package's R_θJA = 200°C/W and P_D = 625 mW at 25°C, derating linearly at 5.0 mW/°C above ambient. The device meets JEDEC TO-92 3L mechanical standards and is rated for continuous collector current up to 200 mA.

Key Specifications

Pinout & Package

2N3904CTA uses the industry-standard TO-92 3-lead through-hole plastic package (JEDEC TO-92), with lead spacing of 0.300 inch (7.62 mm) and body dimensions 4.6 × 3.3 × 4.0 mm. It is supplied in ammo pack (2000 units).

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 2N3904CTA offers optimal balance of legacy compatibility, thermal performance (625 mW), and ease of hand assembly-making it preferred for evaluation, repair, and low-volume production where TO-92 remains standard.

Availability

2N3904CTA is available at Aetrix Electronics and suitable for audio pre-amplifiers, microcontroller interface circuits, signal generator buffers, and industrial sensor signal conditioning requiring stable component supply and long-term obsolescence management.

Supply support for 2N3904CTA 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 2N3904CTA belongs to ON Semiconductor's legacy general-purpose transistor product line, originally developed by Fairchild and maintained for backward-compatible, cost-sensitive linear and switching applications.

FAQ

What is the maximum collector current rating for the 2N3904CTA?

The 2N3904CTA has a continuous collector current rating (I_C) of 200 mA at T_A = 25°C. This value decreases with rising ambient temperature due to its 5.0 mW/°C derating factor. For reliable operation at elevated temperatures, users must calculate junction temperature using R_θJA = 200°C/W and ensure T_J stays within –55°C to +150°C. The 2N3904CTA is not rated for pulsed operation beyond datasheet-defined limits without consultation.

Does the 2N3904CTA have a documented pinout configuration?

Yes, the 2N3904CTA follows the standard TO-92 E-B-C pinout (Emitter-Base-Collector) when viewed with the flat side facing forward and leads pointing downward. Pin 1 is Emitter, Pin 2 is Base, Pin 3 is Collector. This configuration is confirmed in Fairchild/ON Semiconductor documentation and matches JEDEC TO-92 mechanical drawings. The 2N3904CTA pinout is identical across all TO-92 variants including 2N3904BU and 2N3904TF.

What is the typical noise figure of the 2N3904CTA and under what conditions is it measured?

The 2N3904CTA has a typical noise figure (NF) of 5.0 dB, measured at I_C = 100 μA, V_CE = 5.0 V, R_S = 1.0 kΩ, and frequency range 10 Hz to 15.7 kHz. This value reflects its suitability for low-level audio amplification where signal integrity is critical. The 2N3904CTA noise performance remains stable across its specified operating temperature range and is validated in production testing per Rev. 1.1.0 datasheet.

Can the 2N3904CTA be used in switching applications above 10 MHz?

The 2N3904CTA supports switching up to approximately 10 MHz in practical designs, limited by storage time (t_s = 200 ns) and fall time (t_f = 50 ns). While its f_T is 300 MHz, small-signal gain drops significantly above 10 MHz in switching configurations due to charge storage effects. For reliable >10 MHz operation, the 2N3904CTA requires optimized base drive and snubbing; alternative devices like RF-optimized transistors are recommended for sustained >25 MHz use.

Is the 2N3904CTA RoHS compliant and halogen-free?

Yes, the 2N3904CTA is RoHS compliant and halogen-free per ON Semiconductor's material declarations and packaging specifications. It meets EU Directive 2011/65/EU and IEC 61249-2-21:2011 standards. The TO-92 package uses lead-free matte tin plating, and internal die construction excludes brominated flame retardants. Compliance documentation for the 2N3904CTA is available via ON Semiconductor's Quality & Environmental page.