onsemi BD241ATU

Overview

BD241ATU from ON Semiconductor (formerly Fairchild) is an NPN epitaxial silicon power transistor in TO-220 package, rated for 60 V V_CEO, 3 A continuous collector current, and 40 W power dissipation at T_C = 25°C. It serves as a medium-power linear amplifier or switching device in DC motor drivers and power supply output stages.

For engineers reviewing the BD241ATU datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO = 60 V, h_FE ≥ 25 @ I_C = 1 A, V_CE(sat) ≤ 1.2 V @ I_C = 3 A / I_B = 0.6 A, and TO-220 thermal performance under forced-air or heatsink-limited conditions.

Technical Context

The BD241ATU operates as a single NPN bipolar junction transistor with fixed gain structure optimized for medium-power linear and switching applications. Its V_CEO = 60 V and V_CER = 70 V support operation in 48 V rail systems with transient margin, while its 150°C maximum junction temperature enables use in thermally constrained industrial enclosures.

Designed for DC-coupled amplification and hard-switching duty, it features h_FE = 25 (min) at I_C = 1 A and h_FE = 10 (min) at I_C = 3 A, with V_BE(on) = 1.8 V ensuring predictable base drive requirements in discrete driver circuits.

Key Specifications

Pinout & Package

BD241ATU uses the standard TO-220AB package with 3 leads: emitter, base, and collector. The package features a metal tab (collector-connected) for mechanical mounting and thermal conduction to heatsinks.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN power transistor applications.

Compared with BD241ATU, MJD243G offers higher voltage and current but demands SMT requalification, while BD241CTU delivers direct pin-compatible upgrade to 80 V V_CEO with no layout or drive changes-ideal for robustness enhancement in existing TO-220-based power stages.

Availability

BD241ATU is available at Aetrix Electronics and suitable for DC motor control, linear power supplies, relay drivers, and switch-mode power supply auxiliary switching requiring stable component supply across industrial OEM production cycles.

Supply support for BD241ATU 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 BD241ATU belongs to ON Semiconductor's legacy power bipolar transistor family, engineered for cost-sensitive, medium-power linear and switching applications where ruggedness, thermal stability, and complementary pairing matter.

FAQ

What is the maximum continuous collector current rating for BD241ATU?

The BD241ATU has a maximum continuous collector current (I_C) rating of 3 A at case temperature T_C = 25°C. Derating is required above this temperature-approximately 24 mA/°C reduction beyond 25°C per the datasheet thermal curve. This rating applies under proper heatsinking; actual usable current depends on ambient temperature, airflow, and heatsink thermal resistance. BD241ATU must not exceed its 40 W power dissipation limit under any operating condition.

Is BD241ATU pin-compatible with BD241CTU?

Yes, BD241ATU and BD241CTU share identical TO-220AB package dimensions, pin assignment (1=Base, 2=Collector, 3=Emitter), and mechanical footprint. Both devices have the collector internally bonded to the metal tab. However, BD241CTU offers higher V_CEO (80 V vs. 60 V) and V_CER (90 V vs. 70 V), making it a direct drop-in upgrade where enhanced voltage margin is needed without modifying the BD241ATU PCB layout or drive network.

What is the typical DC current gain (h_FE) of BD241ATU at 3 A collector current?

At I_C = 3 A and V_CE = 4 V, the BD241ATU guarantees a minimum h_FE of 10, with typical values ranging between 15 and 25 depending on unit-to-unit variation and temperature. This lower gain at high current reflects the device's optimized saturation behavior-engineers should design base drive circuits to deliver ≥0.6 A to ensure full saturation. BD241ATU's h_FE remains stable across its specified operating range, supporting predictable switching thresholds in relay and motor control applications.

Does BD241ATU have an electrically isolated tab?

No, BD241ATU does not have an electrically isolated tab-the metal tab is internally connected to the collector terminal. This configuration simplifies heatsinking but requires electrical isolation (e.g., mica washer + shoulder washer or insulating thermal pad) when mounting to a grounded heatsink or chassis. Failure to isolate may cause short circuits in common-emitter configurations or violate safety isolation requirements in AC/DC power supplies. Always verify collector potential before mechanical mounting.

Can BD241ATU be used as a replacement for BD241A in existing designs?

Yes, BD241ATU is the modern packaging variant (TO-220AB with lead finish and tape-and-reel option) of the original BD241A, maintaining identical electrical specifications including V_CEO = 60 V, I_C = 3 A, and h_FE min = 25 @ 1 A. The "TU" suffix denotes tape-and-reel packaging for automated assembly, but the die and internal construction are functionally identical. BD241ATU is fully backward compatible with legacy BD241A footprints and drive requirements.