onsemi 2N6518TA

Overview

2N6518TA from ON Semiconductor (formerly Fairchild) is a PNP epitaxial silicon transistor designed for high-voltage switching and amplification in industrial control and power management circuits. It features VCEO = -250 V, IC = -500 mA, PC = 625 mW, hFE = 35–300 (at IC = -1 mA to -100 mA), and TO-92 package. Used in relay drivers and HV DC-DC converter output stages.

For engineers reviewing the 2N6518TA datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP high-voltage breakdown rating, saturation voltage at defined drive conditions, junction temperature limit, and TO-92 mechanical compatibility with legacy through-hole layouts.

Technical Context

This PNP bipolar junction transistor operates with reverse-polarity biasing: collector and emitter voltages are negative relative to base. Its high VCEO and VCBO ratings (-250 V) support use in off-line switch-mode power supply snubber networks and flyback transistor stages where sustained reverse blocking is required.

Dynamic performance includes fT = 40–200 MHz (VCE = -20 V, IC = -10 mA), tON = 200 ns, and tOFF = 3.5 ns under specified test conditions - enabling moderate-speed switching up to ~100 kHz with appropriate base drive design.

Key Specifications

Pinout & Package

2N6518TA is housed in a standard TO-92 plastic package with lead spacing and outline per Fairchild Rev. A2 (August 2002). Pin identification is fixed: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector (viewed with flat side facing user, leads down).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD2955G and BC639, the 2N6518TA uniquely balances -250 V blocking capability, TO-92 form factor, and 625 mW dissipation - making it irreplaceable in space-constrained, high-voltage legacy designs where voltage margin and footprint are non-negotiable.

Availability

2N6518TA is available at Aetrix Electronics and suitable for industrial relay drivers, off-line SMPS snubbers, and legacy equipment repair requiring stable component supply and long-term obsolescence mitigation.

Supply support for 2N6518TA 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

ON Semiconductor is a global semiconductor supplier delivering energy-efficient, high-performance silicon solutions for automotive, industrial, cloud computing, and IoT applications.

The 2N6518TA belongs to Fairchild's legacy high-voltage discrete transistor family, engineered specifically for reliability-critical industrial power switching and repair applications where voltage headroom and through-hole manufacturability are essential.

FAQ

What is the maximum collector-emitter voltage rating for the 2N6518TA?

The 2N6518TA has a maximum collector-emitter voltage rating (VCEO) of -250 V at Ta = 25°C. This rating is confirmed in the Absolute Maximum Ratings table and verified by BVCEO test condition (IC = -1 mA, IB = 0). Operation beyond this voltage risks irreversible avalanche breakdown and device failure. Derating is not specified for VCEO, so -250 V remains the hard limit across the full operating temperature range.

Is the 2N6518TA pin-compatible with the original 2N6518?

Yes, the 2N6518TA is a direct form-fit-function replacement for the legacy 2N6518. Both share identical TO-92 packaging, E-B-C pinout (flat side facing user, leads down), and identical absolute maximum ratings and electrical characteristics per Fairchild Rev. A2 datasheet. The "TA" suffix denotes tape-and-reel packaging but does not alter device specifications or pin assignment.

What is the DC current gain (hFE) range of the 2N6518TA at different collector currents?

The 2N6518TA exhibits hFE = 35–300 depending on operating point: min 35 at IC = -100 mA, min 50 at IC = -30 mA, min 45 at IC = -50 mA, and min 25 at IC = -100 mA (all at VCE = -10 V). The maximum hFE reaches 300 at IC = -1 mA. These values are measured per the Electrical Characteristics table and define base drive requirements across the intended linear and switching load range.

Does the 2N6518TA have a specified thermal resistance (RθJA)?

No, the official Fairchild datasheet for 2N6518TA does not list junction-to-ambient thermal resistance (RθJA). Instead, it specifies collector power dissipation (PC = 625 mW at 25°C) and a linear derating factor of 5 mW/°C above 25°C. Designers must apply these values with board-level thermal modeling or empirical testing, as RθJA depends heavily on PCB copper area, airflow, and mounting method - not inherent to the TO-92 package alone.

Can the 2N6518TA be used as a direct complement to the 2N6515?

Yes, the 2N6518TA is explicitly designated as the PNP complement to the NPN 2N6515 in the datasheet's product description. Both share matching voltage ratings (VCEO = -250 V for 2N6518TA, VCEO = +250 V for 2N6515), similar current capabilities, and TO-92 packaging - enabling symmetrical push-pull or complementary Darlington configurations in high-voltage amplifier and switching applications.