onsemi 2N3903_D74Z

Overview

2N3903_D74Z from Fairchild Semiconductor is an NPN general-purpose bipolar junction transistor (BJT) designed for low-power amplification and switching applications up to 100 mA collector current. It features a V_CEO of 40 V, V_CBO of 60 V, and operates across –55°C to +150°C. Its TO-92 radial ammo packaging (EOL code D74Z) supports automated assembly in consumer audio preamps, sensor interface stages, and discrete logic level translators.

For engineers reviewing the 2N3903_D74Z datasheet, pinout, applications, or equivalent options, key selection criteria include verified DC current gain (h_FE = 15–150 at I_C = 0.1–100 mA), low saturation voltage (V_CE(sat) = 0.2 V @ I_C = 10 mA/I_B = 1 mA), thermal resistance (R_θJA = 200°C/W), and TO-92 mechanical compatibility with legacy through-hole designs.

Technical Context

The 2N3903_D74Z implements a planar epitaxial NPN structure optimized for stable h_FE across temperature and bias conditions. Its base-emitter junction exhibits V_BE(sat) = 0.65–0.95 V at I_C = 10–50 mA, enabling predictable turn-on in saturated switch configurations. Small-signal parameters include h_fe = 50–200 at f = 1 kHz and noise figure NF = 6.0 dB at 100 µA/1 kHz bandwidth.

Thermal design relies on R_θJA = 200°C/W and P_D = 625 mW at T_A = 25°C, derating linearly at 5.0 mW/°C above ambient. Switching performance is characterized by t_d = 35 ns, t_r = 35 ns, t_s = 175 ns, and t_f = 50 ns under pulsed test conditions (≤300 µs, ≤2% duty cycle).

Key Specifications

Pinout & Package

2N3903_D74Z uses the standard TO-92 plastic package with axial leads and flat side orientation. The D74Z ammo packaging variant specifies collector-first lead orientation (first wire off is collector), flat side on top, and adhesive tape on bottom side - critical for correct automated placement alignment.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2N3903_D74Z, the 2N3904 offers superior gain uniformity below 10 mA but reduced safe operating area above 50 mA, while BC547B provides higher voltage tolerance at the cost of mechanical and electrical requalification.

Availability

2N3903_D74Z is available at Aetrix Electronics and suitable for audio pre-amplifiers, sensor signal conditioning, discrete logic level translation, and low-power relay drivers requiring stable component supply and legacy TO-92 compatibility.

Supply support for 2N3903_D74Z 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

Fairchild Semiconductor was a U.S.-based semiconductor manufacturer specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The 2N3903_D74Z belongs to Fairchild's legacy general-purpose BJT product line, engineered for cost-sensitive, high-reliability linear and switching functions in consumer, industrial, and automotive auxiliary systems.

FAQ

What is the pin configuration of the 2N3903_D74Z?

The 2N3903_D74Z uses the standard TO-92 package with Emitter-Base-Collector (E-B-C) pinout when viewed with the flat side facing forward and leads pointing downward. The D74Z ammo packaging variant specifies collector-first lead orientation, meaning the first lead exiting the tape is the collector terminal - critical for automated placement verification.

Does the 2N3903_D74Z support switching applications up to 100 mA?

Yes, the 2N3903_D74Z is rated for continuous collector current up to 200 mA, with recommended operation up to 100 mA per its official application description. At I_C = 100 mA and I_B = 10 mA, V_CE(sat) remains ≤ 0.3 V, ensuring efficient saturated switching with minimal power loss in the 2N3903_D74Z.

What is the maximum operating temperature for the 2N3903_D74Z?

The 2N3903_D74Z has a specified junction temperature range of –55°C to +150°C, with thermal resistance R_θJA = 200°C/W. To maintain reliability at +150°C junction temperature, ambient must be limited based on power dissipation - for example, at 300 mW, maximum ambient is ~0°C without heatsinking.

How does the 2N3903_D74Z compare to the 2N3904 in terms of DC current gain?

The 2N3903_D74Z specifies h_FE = 35 min at I_C = 1 mA, while the 2N3904 guarantees h_FE = 100 min under identical conditions. Both share identical V_CEO, V_CBO, and TO-92 packaging, making the 2N3904 preferable for low-current amplification where gain predictability is essential in the 2N3903_D74Z's intended use cases.

Is the 2N3903_D74Z RoHS compliant?

The 2N3903_D74Z was manufactured prior to full RoHS enforcement and is classified as a legacy component. While it contains no intentionally added lead beyond solder alloy exemptions, formal RoHS certification documentation is not available. For new designs requiring compliance, consult Aetrix Electronics for qualified replacements or reflow profile guidance.