onsemi 2N6518BU

Overview

2N6518BU from Fairchild Semiconductor is a PNP epitaxial silicon transistor rated for high-voltage switching applications, with VCEO = -250 V, IC = -500 mA, PC = 625 mW, hFE = 35–300 (at IC = -1 mA to -100 mA), and fT = 40–200 MHz. It serves as a high-voltage switch or amplifier in flyback converters, relay drivers, and industrial control circuits.

For engineers reviewing the 2N6518BU datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP polarity, TO-92 package compatibility, breakdown voltage margin at -250 V, saturation performance under -50 mA/-5 mA drive, and thermal derating of 5 mW/°C above 25°C.

Technical Context

This device operates as a medium-power, high-voltage PNP bipolar junction transistor optimized for linear amplification and fast-switching duty. Its structure features epitaxial base construction enabling stable hFE across collector current range (-1 mA to -100 mA) and low saturation voltages (VCE(sat) ≤ -0.50 V at IC = -30 mA/IB = -3 mA).

Designed for operation up to TJ = 150°C, it supports pulse-mode switching with tON = 200 ns and tOFF = 3.5 ns under specified test conditions (VCC = -100 V, IC = -50 mA). Capacitance values (Cob = 6 pF, CEB = 100 pF) reflect trade-offs between speed and voltage rating in high-VCEO PNP topology.

Key Specifications

Pinout & Package

2N6518BU is housed in a standard TO-92 plastic package with lead spacing and outline per Fairchild's published dimensions (14.47 mm length, 4.58 mm width, 3.86 mm height max). Pin identification: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP high-voltage switching applications.

Compared with 2N6518BU, MPSA92 offers enhanced voltage robustness for harsher transients while retaining identical footprint and drive requirements; 2N4403 trades voltage capability for improved low-current gain predictability but cannot replace 2N6518BU in ≥100 V applications.

Availability

2N6518BU is available at Aetrix Electronics and suitable for industrial relay drivers, offline flyback snubber circuits, linear audio preamplifiers, and high-voltage level shifters requiring stable component supply and long-term obsolescence management.

Supply support for 2N6518BU 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 designer and manufacturer of analog and discrete semiconductors, acquired by ON Semiconductor in 2016; its legacy product lines remain widely supported in industrial and automotive applications.

The 2N6518BU belongs to Fairchild's general-purpose high-voltage PNP transistor family, developed for cost-sensitive, reliability-critical switching and amplification tasks in power supplies, controls, and instrumentation where TO-92 form factor and -250 V rating are essential.

FAQ

What is the maximum safe operating voltage for 2N6518BU?

The 2N6518BU has absolute maximum ratings of VCBO = -250 V and VCEO = -250 V at Ta = 25°C. Operation must remain within these limits, with appropriate derating for temperature and reliability margin. Sustained operation above -225 V is not recommended without transient protection and thermal validation. The 2N6518BU must never be biased beyond its rated breakdown voltages in any mode.

Does 2N6518BU have a documented pinout compatible with standard TO-92 footprints?

Yes, the 2N6518BU uses the industry-standard TO-92 package with pin configuration: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector - matching JEDEC TO-92 outline and compatible with common PCB footprints. Mechanical drawings confirm 1.27 mm lead pitch and 4.58 mm body width, ensuring mechanical fit in legacy and new designs using this outline.

What is the typical DC current gain (hFE) of 2N6518BU at 10 mA collector current?

Per the official Fairchild datasheet, the 2N6518BU exhibits hFE = 50 (minimum) to 220 (maximum) at VCE = -10 V and IC = -10 mA. Typical hFE under these conditions is approximately 100–130. This gain range must be accounted for in bias network design, especially in linear amplifier or precision switch applications where gain variation affects stability.

Can 2N6518BU be used in switching power supplies above 100 kHz?

Yes - the 2N6518BU has tOFF = 3.5 ns and fT = 40–200 MHz, supporting reliable operation in PWM-based switching supplies up to ~150 kHz. However, switching losses increase significantly above 100 kHz due to finite charge storage; layout optimization and gate/base drive strength must be validated. The 2N6518BU remains viable for auxiliary or snubber switches in such topologies.

Is 2N6518BU still in active production and supported by ON Semiconductor?

The 2N6518BU is a legacy Fairchild part discontinued after acquisition by ON Semiconductor. While no longer in active production, it remains available through authorized distributors and Aetrix Electronics with traceable, date-code-verified inventory. ON Semiconductor does not list 2N6518BU in current active portfolios but supports cross-reference and obsolescence mitigation for this part.