onsemi 2N5401NLBU

Overview

2N5401NLBU from Fairchild Semiconductor is a PNP epitaxial silicon small-signal transistor rated for -150 V V_CEO, -600 mA I_C, and 625 mW power dissipation in TO-92 package, commonly used in high-voltage amplifier and switching stages of analog signal conditioning and relay driver circuits.

For engineers reviewing the 2N5401NLBU datasheet, pinout, applications, or equivalent options, key selection considerations include its -150 V collector-emitter breakdown rating, DC current gain range of 30–240 at I_C = -1 to -50 mA, saturation voltage below -0.5 V at -50 mA, 100–400 MHz f_T, and low 6 pF output capacitance at -10 V V_CB.

Technical Context

This PNP bipolar junction transistor operates with reverse-polarity biasing: emitter positive relative to base and collector. Its high V_CEO (-150 V) and V_CBO (-160 V) support use in off-line or flyback auxiliary supply stages where voltage transients exceed 100 V. The device exhibits h_FE = 30 min at I_C = -1 mA and h_FE = 50 min at I_C = -50 mA, with V_CE(sat) ≤ -0.5 V under forced β = 10.

Noise figure is specified at 8 dB (10 Hz–15.7 kHz, R_S = 1 kΩ), confirming suitability for low-frequency audio preamplifier input stages. Cob = 6 pF at V_CB = -10 V enables stable operation in tuned RF amplifier applications up to ~100 MHz.

Key Specifications

Pinout & Package

2N5401NLBU is housed in a standard TO-92 plastic package with lead finish optimized for wave soldering and automated assembly. Dimensions conform to JEDEC TO-92 outline: body height 4.58 mm max, lead spacing 1.27 mm, overall length 4.58 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP small-signal transistor applications.

Compared with MPSA92 and BC557B, the 2N5401NLBU offers optimal balance of high-voltage tolerance (-150 V), moderate gain (30–240), and proven thermal stability in TO-92-making it preferred for industrial relay drivers and flyback feedback stages where both voltage headroom and reliability are critical.

Availability

2N5401NLBU is available at Aetrix Electronics and suitable for industrial control systems, telecom line interface modules, and analog signal conditioning circuits requiring stable component supply and long-term manufacturability.

Supply support for 2N5401NLBU 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 2N5401NLBU belongs to Fairchild's legacy general-purpose PNP transistor family designed for high-voltage linear amplification and robust switching in industrial and telecom infrastructure equipment.

FAQ

What is the pin configuration of the 2N5401NLBU?

The 2N5401NLBU uses a standard TO-92 package with pinout: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector. This configuration is confirmed in Fairchild's Rev. B datasheet and matches JEDEC TO-92 mechanical drawings. The device is not pin-compatible with NPN variants like 2N5551, and substitution requires circuit polarity reversal.

Does the 2N5401NLBU support operation at elevated temperatures?

Yes, the 2N5401NLBU has a maximum junction temperature of 150°C and storage temperature range of -55°C to +150°C. Derating is required above 25°C ambient: power dissipation must be reduced linearly to zero at 150°C case temperature. At 75°C ambient, maximum allowable P_C is approximately 450 mW per thermal resistance data in the datasheet.

What is the typical noise performance of the 2N5401NLBU in audio applications?

The 2N5401NLBU has a specified noise figure of 8 dB at I_C = -250 µA, V_CE = -5 V, R_S = 1 kΩ, and frequency range 10 Hz to 15.7 kHz. This makes it suitable for low-level audio preamplifier stages where SNR preservation is critical, though lower-noise alternatives like BC550C may be preferred for ultra-low-noise microphone inputs.

Can the 2N5401NLBU replace the 2N5401 in existing designs?

Yes, the 2N5401NLBU is a direct replacement for the base 2N5401. The "NLBU" suffix denotes a specific tape-and-reel packaging variant with lead finish optimized for automated assembly; all electrical and thermal specifications-including V_CEO, h_FE, and f_T-are identical to the original 2N5401 as documented in Fairchild's Rev. B datasheet.

Is the 2N5401NLBU suitable for RF amplifier use?

Yes, the 2N5401NLBU has a current gain bandwidth product (f_T) of 100–400 MHz and output capacitance (C_ob) of 6 pF at -10 V V_CB, supporting stable common-emitter amplification up to ~30 MHz. It is commonly used in HF oscillator and IF amplifier stages, though layout parasitics and proper biasing are essential to maintain gain and stability.