Microchip Technology 2N6547

Overview

2N6547 from STMicroelectronics is a high-voltage, high-current silicon NPN bipolar junction transistor in a TO-3 metal package, designed for industrial switching applications including flyback and forward single-transistor low-power converters. It delivers 850 V VCER/VCES, 400 V VCEO, 15 A continuous collector current, and 175 W total dissipation at Tc = 25 °C.

For engineers reviewing the 2N6547 datasheet, 2N6547 pinout, 2N6547 application, or 2N6547 equivalent, key selection criteria include sustaining voltage under inductive load (VCEO(sus) = 400 V), fast switching performance (ts = 5 µs, tf = 1.5 µs at Tc = 100 °C), thermal resistance (Rthj-case = 1 °C/W), and ruggedness for mains-connected SMPS designs.

Technical Context

The 2N6547 employs a multiepitaxial mesa structure to achieve high breakdown voltage and robust secondary breakdown immunity. Its design supports operation directly from single- or three-phase AC mains with minimal external snubbing due to high VCEO(sus) and controlled storage time.

It operates with base-driven control (IB ≤ 4 A continuous), exhibits hFE = 6–30 at IC = 5–10 A, and maintains VCE(sat) ≤ 2.5 V at IC = 15 A / IB = 3 A - enabling efficient hard-switching in offline converters below 100 W.

Key Specifications

Pinout & Package

Package: TO-3 metal case with electrically isolated collector tab. Mounting hole centered on collector terminal; emitter and base leads extend from base of case.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BU2508AX and 2SD1403, the 2N6547 offers superior voltage headroom (850 V VCER), higher current capacity (15 A), and faster inductive switching - making it uniquely suitable for universal-input, compact, and thermally constrained offline SMPS designs.

Availability

2N6547 is available at Aetrix Electronics and suitable for switch-mode power supplies, flyback converters, and industrial motor control circuits requiring stable component supply and long-term manufacturability.

Supply support for 2N6547 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power discrete devices, microcontrollers, and analog ICs for industrial and automotive markets.

The 2N6547 belongs to ST's high-voltage bipolar transistor product line, engineered specifically for rugged, cost-effective switching in offline AC-DC conversion and industrial power control.

FAQ

What is the maximum safe operating voltage for 2N6547 in a flyback circuit?

The 2N6547 supports up to 400 V VCEO under zero-base-current conditions, verified with inductive load testing (L = 25 mH). For flyback applications, its 400 V VCEO(sus) rating - measured at IC = 100 mA - defines the practical upper limit for reflected voltage across the primary winding. Exceeding this requires external clamping or snubbing.

Can 2N6547 be used in parallel for higher current?

No - the 2N6547 lacks built-in emitter ballasting or matched hFE characteristics required for stable current sharing. Its multiepitaxial mesa structure yields non-uniform current distribution under parallel bias. STMicroelectronics does not recommend paralleling; instead, use a single device with adequate SOA margin or select a higher-rated alternative like the 2N6549.

What base drive current is required for full saturation at 15 A collector current?

Full saturation at IC = 15 A requires IB = 3 A, as specified in the VCE(sat) test condition. The datasheet confirms VCE(sat) ≤ 2.5 V under this drive. Base drive must sustain ≥3 A peak with <100 ns rise/fall times to minimize storage time and switching loss in hard-switched topologies.

Is the TO-3 case electrically isolated from the collector?

No - the metal TO-3 case is internally bonded to the collector terminal. This is confirmed by mechanical drawings showing the collector tab as the mounting surface and electrical schematics indicating collector-to-case continuity. An insulating washer and shoulder washer are mandatory when mounting to a grounded heatsink.