onsemi BD241BTU

Overview

BD241BTU from Fairchild Semiconductor is an NPN epitaxial silicon power transistor in TO-220 package, rated for 80 V V_CEO, 3 A DC collector current, and 40 W collector dissipation at T_C=25°C, commonly used in medium-power linear regulators and switching power supplies.

For engineers reviewing the BD241BTU datasheet, pinout, applications, or equivalent options, key selection factors include V_CEO rating, h_FE consistency at 1–3 A, V_CE(sat) under 1.2 V at I_C=3 A/I_B=0.6 A, and thermal performance in TO-220 mounting configurations.

Technical Context

The BD241BTU operates as a medium-power bipolar junction transistor with fixed NPN polarity and epitaxial base construction, supporting both linear amplification and hard-switching modes. Its sustaining voltage V_CEO(sus) is specified at 80 V with I_C = −30 mA and I_B = 0, and leakage currents (I_CEO, I_CES) are characterized up to V_CE = 80 V.

DC current gain h_FE is guaranteed ≥25 at V_CE = 4 V, I_C = 1 A and ≥10 at V_CE = 4 V, I_C = 3 A, indicating usable gain across its rated current range. Saturation behavior is defined by V_CE(sat) ≤1.2 V and V_BE(on) ≤1.8 V under specified drive conditions.

Key Specifications

Pinout & Package

BD241BTU is housed in a through-hole TO-220 package with standard 3-pin configuration: Pin 1 = Base, Pin 2 = Collector (tab), Pin 3 = Emitter. The metal tab is electrically connected to the collector and must be insulated if mounted to a grounded heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD243G and BD241C, the BD241BTU offers optimal balance of proven TO-220 thermal performance, 80 V robustness, and cost efficiency for industrial linear and switching applications without requiring SMT reflow or premium voltage margin.

Availability

BD241BTU is available at Aetrix Electronics and suitable for linear voltage regulators, DC motor drivers, switch-mode power supplies, and audio amplifier output stages requiring stable component supply and long-term industrial availability.

Supply support for BD241BTU 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 discrete devices, analog ICs, and interface solutions before its acquisition by ON Semiconductor in 2016.

The BD241BTU belongs to Fairchild's BD241/A/B/C family of medium-power NPN transistors designed specifically for industrial linear regulation, switching power conversion, and motor control where ruggedness, predictable gain, and thermal reliability are essential.

FAQ

What is the maximum collector-emitter voltage rating for BD241BTU?

The BD241BTU has a maximum collector-emitter voltage (V_CEO) rating of 80 V at T_C = 25°C. This value is confirmed in the Absolute Maximum Ratings table and matches the V_CEO(sus) specification under pulsed test conditions. Exceeding this voltage risks avalanche breakdown and permanent device failure.

Is BD241BTU pin-compatible with other variants in the BD241 family?

Yes, BD241BTU shares identical TO-220 package dimensions and pinout (Base–Collector–Emitter) with BD241, BD241A, and BD241C. All variants use Pin 1 = Base, Pin 2 = Collector (tab), Pin 3 = Emitter. However, V_CEO ratings differ: BD241 = 45 V, BD241A = 60 V, BD241B = 80 V (BD241BTU), BD241C = 100 V.

What is the typical DC current gain (h_FE) of BD241BTU at 3 A collector current?

The BD241BTU guarantees h_FE ≥10 at V_CE = 4 V and I_C = 3 A, per the Electrical Characteristics table. While typical values may reach 15–20 under those conditions, design must rely on the minimum guaranteed value of 10 to ensure sufficient base drive margin in production circuits.

Can BD241BTU be used in switching applications with 100 kHz PWM?

Yes, BD241BTU is qualified for medium-frequency switching such as 50–100 kHz in flyback or forward converters. Its specified pulse current I_CP = 5 A (PW = 350 µs, duty cycle ≤2%) and V_CE(sat) ≤1.2 V support efficient hard-switching, though switching speed is limited by minority-carrier storage time-not optimized for >200 kHz operation.

Does BD241BTU require heatsinking in continuous 3 A operation?

Yes, BD241BTU requires a heatsink in continuous 3 A operation. At full I_C and V_CE(sat) = 1.2 V, conduction loss alone reaches 3.6 W. With a junction-to-case thermal resistance of ~1.25°C/W (typical for TO-220), even modest ambient temperatures exceed the 150°C T_J limit without heatsinking-making thermal management mandatory.