onsemi 2N4400TFR

Overview

2N4400TFR 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) = 0.40–0.75 V. It is commonly used in low-voltage DC-DC converter control stages and discrete logic-level switching circuits.

For engineers reviewing the 2N4400TFR datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO/I_C ratings, h_FE consistency across operating current range, saturation voltage at design-relevant I_B/I_C ratios, thermal resistance (R_θJA = 200 °C/W), and TO-92 mechanical compatibility.

Technical Context

The 2N4400TFR operates as a single NPN silicon BJT with fixed-emitter configuration and no integrated biasing or protection circuitry. Its DC current gain (h_FE) varies significantly with collector current - from ≥20 at I_C = 1 mA to ≥50 at I_C = 150 mA - requiring explicit gain-dependent bias network design. Saturation behavior is characterized at two drive levels: V_CE(sat) = 0.40 V @ I_C = 150 mA / I_B = 15 mA and 0.75 V @ I_C = 500 mA / I_B = 50 mA.

Switching performance is defined by delay (t_d = 15 ns), rise (t_r = 20 ns), storage (t_s = 225 ns), and fall (t_f = 30 ns) times under pulsed conditions (≤300 µs width, ≤2% duty cycle). Small-signal parameters include h_fe = 2.0 @ f = 100 MHz (I_C = 20 mA), C_ob = 6.5 pF, and C_ib = 30 pF, supporting mid-frequency amplifier use up to ~50 MHz.

Key Specifications

Pinout & Package

2N4400TFR is housed in a through-hole TO-92 package (JEDEC TO-92 variant), with standardized lead assignment: Emitter (E), Base (B), Collector (C) - left-to-right when viewing flat side with leads down.

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 2N4400TFR provides the highest continuous collector current (600 mA) and lowest thermal resistance (200 °C/W) in a through-hole package, making it optimal for cost-sensitive, medium-power discrete switching where manual assembly or socketing is preferred.

Availability

2N4400TFR is available at Aetrix Electronics and suitable for relay driver stages, DC-DC converter switches, and logic-level interface circuits requiring stable component supply and long-term industrial availability.

Supply support for 2N4400TFR 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 components before its acquisition by ON Semiconductor in 2016.

The 2N4400TFR belongs to Fairchild's legacy general-purpose BJT family, engineered for cost-effective, robust discrete switching and amplification in industrial control, power conversion, and interface circuits.

FAQ

What is the maximum continuous collector current rating for the 2N4400TFR?

The 2N4400TFR has a maximum continuous collector current (I_C) rating of 600 mA at T_A = 25°C, with functional use validated up to 500 mA in switching and amplification roles. Derating is required above 25°C per its 200 °C/W R_θJA; at 70°C ambient, max usable I_C drops to approximately 420 mA to maintain T_J ≤ 150°C. This rating is confirmed in the Absolute Maximum Ratings table of the official Fairchild datasheet Rev A.

Is the 2N4400TFR pin-compatible with the MMBT4400?

No, the 2N4400TFR is not pin-compatible with the MMBT4400 due to differing packages: 2N4400TFR uses TO-92 (through-hole, leads down, E-B-C left-to-right), while MMBT4400 uses SOT-23 (surface-mount, bottom view, E-B-C left-to-right but with different pad layout and pitch). Though electrically identical, PCB layout and assembly process differ; direct substitution requires mechanical redesign. The 2N4400TFR datasheet explicitly shows both packages separately with distinct pin diagrams.

What is the typical h_FE of the 2N4400TFR at 10 mA collector current?

The typical h_FE of the 2N4400TFR at V_CE = 1.0 V and I_C = 10 mA is 40–100, with a minimum guaranteed value of 40 per the Electrical Characteristics table. This range reflects unit-to-unit variation and is consistent across production lots. Designers should use the minimum value (40) for worst-case bias calculations; the 2N4400TFR datasheet confirms this under "ON CHARACTERISTICS" with test condition V_CE = 1.0 V, I_C = 10 mA.

Does the 2N4400TFR support linear amplification applications?

Yes, the 2N4400TFR supports linear amplification, with verified h_fe = 20–250 at I_C = 1.0–20 mA and V_CE = 10 V, and input impedance (h_ie) = 0.5–7.5 kΩ at 1 kHz. Its Cob = 6.5 pF and Cib = 30 pF enable stable mid-band gain up to ~50 MHz. The datasheet includes Typical Common Emitter Characteristics curves confirming linearity across V_CE = 0.5–25 V and I_C = 0.1–100 mA, validating use in audio preamps and sensor signal conditioning.

What is the storage time (t_s) specification for the 2N4400TFR?

The storage time (t_s) for the 2N4400TFR is specified as 225 ns under pulsed test conditions: V_CC = 30 V, I_C = 150 mA, I_B1 = I_B2 = 15 mA. This parameter is critical for calculating minimum off-time in PWM-driven switching applications and appears in the "SWITCHING CHARACTERISTICS" section of the Fairchild 2N4400/MMBT4400 datasheet Rev A. It reflects minority-carrier removal delay and is temperature-dependent, increasing at higher junction temperatures.