onsemi 2N4400TAR

Overview

2N4400TAR from Fairchild Semiconductor is an NPN general-purpose bipolar junction transistor (BJT) designed for amplification and switching applications up to 500 mA collector current. It features V_CEO = 40 V, V_CBO = 60 V, V_EBO = 6.0 V, h_FE = 20–150 (at I_C = 1–500 mA), and V_CE(sat) = 0.40 V (at I_C = 150 mA, I_B = 15 mA). It is commonly used in low-voltage DC-DC converter control stages and signal-level switching in industrial sensor interfaces.

For engineers reviewing the 2N4400TAR datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO/I_C ratings, h_FE consistency across operating current range, thermal resistance (R_θJA = 200 °C/W), saturation voltage behavior at target drive conditions, and TO-92 mechanical compatibility for through-hole prototyping and legacy board replacement.

Technical Context

The 2N4400TAR operates as a single NPN BJT with fixed emitter-base and collector-base junction structures optimized for linear amplification and hard-switching. Its h_FE varies significantly with I_C-from ≥20 at 1 mA to ≥50 at 150 mA-requiring bias network validation across load conditions. Saturation performance is characterized at two drive levels: 15 mA/150 mA and 50 mA/500 mA, confirming usable gain compression under switching duty.

Thermal design must account for its R_θJA = 200 °C/W (TO-92) and P_D = 625 mW at T_A = 25°C, derating by 5.0 mW/°C above ambient. The device supports operation from −55°C to +150°C junction temperature, with V_(BR)CEO tested at I_C = 1.0 mA and I_EX ≤ 0.1 µA at V_CE = 35 V, indicating tight leakage control for standby-sensitive circuits.

Key Specifications

Pinout & Package

2N4400TAR is supplied in TO-92 plastic package (3-lead, through-hole), with standard pinout: Emitter (E), Base (B), Collector (C) - left-to-right when flat side faces viewer and leads point downward.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT4400 and 2N3904, the 2N4400TAR delivers higher continuous collector current (600 mA vs. 350 mA and 200 mA), validated thermal performance in TO-92, and proven reliability in legacy industrial assemblies-making it the preferred choice for through-hole designs requiring robust 500 mA switching capability.

Availability

2N4400TAR is available at Aetrix Electronics and suitable for industrial relay drivers, low-voltage DC-DC feedback switches, and legacy audio preamp stages requiring stable component supply and long-term obsolescence mitigation.

Supply support for 2N4400TAR 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 company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.

The 2N4400TAR belongs to Fairchild's legacy general-purpose BJT product line, engineered for cost-effective, reliable amplification and switching in industrial control, power supply, and sensor interface applications.

FAQ

What is the maximum continuous collector current rating for the 2N4400TAR?

The 2N4400TAR has a maximum continuous collector current (I_C) rating of 600 mA at T_A = 25°C, with datasheet-recommended operation up to 500 mA for sustained switching duty. Derating applies above 25°C ambient per the 5.0 mW/°C thermal coefficient. This rating is validated under steady-state DC conditions-not pulsed operation-and must be verified against actual board-level thermal performance when deployed in enclosed environments.

Is the 2N4400TAR pin-compatible with the MMBT4400?

No, the 2N4400TAR is not pin-compatible with the MMBT4400. The 2N4400TAR uses a TO-92 through-hole package with E-B-C lead order (left-to-right, flat side facing), while the MMBT4400 uses an SOT-23 surface-mount package with different pin mapping and solder footprint. Though electrically similar, they require separate PCB layouts and assembly processes. The 2N4400TAR remains the correct choice for legacy TO-92 designs.

What is the typical V_CE(sat) of the 2N4400TAR under switching conditions?

The 2N4400TAR specifies V_CE(sat) = 0.40 V at I_C = 150 mA and I_B = 15 mA, and 0.75 V at I_C = 500 mA and I_B = 50 mA. These values are measured under pulsed test conditions (≤300 µs, ≤2% duty cycle) and represent worst-case saturation voltage for hard-switching applications. Designers should verify actual V_CE(sat) under their specific drive and thermal conditions, as self-heating increases voltage drop at high duty cycles.

Does the 2N4400TAR meet RoHS requirements?

Yes, the 2N4400TAR manufactured by Fairchild Semiconductor complies with RoHS Directive 2011/65/EU, including exemption 7a for lead in high-melting-temperature type solders. Lead content is restricted to ≤0.1 wt% in homogeneous materials, and all packaging materials are halogen-free per JEDEC J-STD-709. Certifications are documented in Fairchild's material declarations dated prior to the ON Semiconductor acquisition.

Can the 2N4400TAR be used in linear amplifier configurations?

Yes, the 2N4400TAR is explicitly characterized for linear amplification, with h_FE data provided across I_C = 1–500 mA and V_CE = 1–2 V, plus small-signal parameters (h_fe, h_ie, h_oe) at 1–100 MHz. Its typical h_FE of 50 at I_C = 150 mA supports stable Class-A or emitter-degenerated common-emitter stages. However, designers must ensure junction temperature stays within −55°C to +150°C limits and avoid operation near V_CEO or P_D boundaries during signal peaks.