onsemi 2N4401NLBU

Overview

2N4401NLBU from onsemi is an NPN general-purpose bipolar junction transistor (BJT) designed for medium-power amplification and switching applications with continuous collector current up to 600 mA, V_CEO = 40 V, and DC current gain (h_FE) ranging from 40 to 300 at I_C = 1.0–150 mA. It operates across –55°C to +150°C and is commonly used in relay drivers, LED drivers, and low-frequency signal amplification stages.

For engineers reviewing the 2N4401NLBU datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92 package thermal resistance (R_θJA = 200°C/W), saturation voltage (V_CE(sat) = 0.40 V @ I_C = 150 mA), f_T = 250 MHz bandwidth, and compatibility with through-hole prototyping and industrial control PCBs.

Technical Context

The 2N4401NLBU implements a silicon planar epitaxial NPN structure optimized for linear amplification and saturated switching. Its h_FE exhibits strong current dependency-minimum 40 at I_C = 1.0 mA and 100 at I_C = 150 mA-with guaranteed V_BE(sat) ≤ 0.95 V under same conditions.

Thermal performance is defined by a 625 mW total power dissipation at T_A = 25°C, derating linearly at 5.0 mW/°C above ambient. Switching behavior is characterized by t_d = 15 ns, t_r = 20 ns, t_s = 225 ns, and t_f = 30 ns under specified test conditions (V_CC = 30 V, I_C = 150 mA).

Key Specifications

Pinout & Package

2N4401NLBU uses the standard TO-92 3-lead through-hole package with straight leads (JEDEC TO-92 compliant). Pin identification follows the EBC (Emitter-Base-Collector) sequence when viewing the flat side with leads downward.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN switching and amplification applications.

Compared with 2N4401NLBU, the 2N2222A offers higher current headroom but looser h_FE control, while the BC547B delivers superior gain consistency at lower power-making 2N4401NLBU the optimal balance of current capability, thermal robustness, and gain predictability for general-purpose 150–500 mA switching.

Availability

2N4401NLBU is available at Aetrix Electronics and suitable for relay drivers, LED current switches, and audio preamplifier stages requiring stable component supply, long-term manufacturability, and JEDEC-standard through-hole compatibility.

Supply support for 2N4401NLBU 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 manufacturer specializing in energy-efficient power management, analog, sensors, and logic devices for automotive, industrial, and consumer markets.

The 2N4401NLBU belongs to onsemi's legacy general-purpose BJT product line, engineered for reliability and broad compatibility in cost-sensitive, high-volume linear and switching applications across industrial controls and legacy electronics.

FAQ

What is the pin configuration of the 2N4401NLBU?

The 2N4401NLBU uses a TO-92 package with E-B-C (Emitter-Base-Collector) pinout when viewed from the flat side with leads pointing downward and left-to-right as Lead 1–2–3. This matches JEDEC standard orientation and is verified in Figure 15 of the official onsemi datasheet MMBT4401/D. The 2N4401NLBU pinout is identical to industry-standard 2N4401 variants and supports direct replacement in existing TO-92 footprints.

Does the 2N4401NLBU support switching at 1 MHz?

The 2N4401NLBU has a transition frequency f_T of 250 MHz and measured switching times (t_d = 15 ns, t_r = 20 ns, t_f = 30 ns) that support clean 1 MHz square-wave operation in saturated switching mode. However, storage time t_s = 225 ns limits practical duty-cycle agility; for reliable 1 MHz switching, ensure sufficient off-time (>500 ns) to fully remove stored charge. The 2N4401NLBU remains effective for this frequency in non-critical timing applications.

What is the maximum power dissipation of the 2N4401NLBU at 75°C ambient?

At T_A = 75°C, the 2N4401NLBU's maximum power dissipation is calculated as P_D = 625 mW − (5.0 mW/°C × (75 − 25)) = 375 mW. This value assumes no heatsink and standard FR-4 PCB mounting per datasheet Note 3. Exceeding this limit risks junction temperature exceeding 150°C. Derating must be applied continuously-not just at peak load-for long-term reliability of the 2N4401NLBU.

Can the 2N4401NLBU replace the MMBT4401 in a design?

No-the 2N4401NLBU and MMBT4401 are not interchangeable due to fundamental differences: the 2N4401NLBU uses TO-92 packaging (R_θJA = 200°C/W, P_D = 625 mW), while the MMBT4401 uses SOT-23 (R_θJA = 357°C/W, P_D = 350 mW). Their pinouts, thermal performance, and current capabilities differ significantly. Substituting the 2N4401NLBU for MMBT4401 would require PCB layout changes and thermal revalidation; the 2N4401NLBU is not a drop-in replacement.

Is the 2N4401NLBU suitable for linear amplifier applications?

Yes-the 2N4401NLBU is explicitly characterized for linear operation with h_FE, h_ie, h_re, h_fe, and h_oe parameters specified at I_C = 1.0 mA and V_CE = 10 V. Its f_T = 250 MHz and low noise profile support audio-frequency amplification, and typical performance curves (Figures 12–14) confirm stable common-emitter gain across collector voltages. For best linearity, bias the 2N4401NLBU at I_C = 1–10 mA with emitter degeneration.