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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

STMicroelectronics BD241A-A

Name: BD241A-A
Brand: STMicroelectronics
SKU: BD241A-A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD241A-A

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BD241A-A.pdf

Description:: TRANS NPN 60V 3A TO-220

Quantity:: RFQ Add To RFQ list

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Inventory:6,750

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Product details

Overview

BD241A-A from STMicroelectronics is an NPN power transistor qualified for automotive applications, featuring 60 V V_CEO, 3 A continuous collector current, 40 W total dissipation at T_case = 25°C, and low 1.2 V V_CE(sat) at I_C = 3 A / I_B = 0.6 A, used in audio amplifier output stages and high-current switching circuits.

For engineers reviewing the BD241A-A datasheet, BD241A-A pinout, BD241A-A application, or BD241A-A equivalent, key selection criteria include safe operating area (SOA) compliance at 150°C junction temperature, automotive-grade qualification per AEC-Q101, TO-220 mechanical robustness, and verified h_FE ≥25 at I_C = 1 A.

Technical Context

This planar NPN transistor uses "Base Island" layout to achieve high DC current gain and low saturation voltage. It operates with V_CEO = 60 V, I_C = 3 A, and supports pulsed collector current up to 5 A (t_p < 1 ms), enabling use in linear and switching modes with thermal derating above 25°C case temperature.

The device exhibits I_CES ≤ 0.2 mA at rated V_CEO, V_BE = 1.8 V at I_C = 3 A, and h_FE = 10 at I_C = 3 A - confirming stable gain across load range and suitability for Class AB audio output stages and relay drivers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 V - maximum collector-emitter voltage with base open; defines safe blocking capability in switching applications
I_C (continuous)	3 A - continuous collector current rating at T_case = 25°C; sets baseline for heatsink sizing
P_TOT	40 W - total power dissipation at T_case = 25°C; determines thermal margin before derating begins
V_CE(sat)	1.2 V @ I_C = 3 A, I_B = 0.6 A - low saturation voltage minimizes conduction loss in switch-mode operation
h_FE	25 min @ I_C = 1 A, V_CE = 4 V - ensures reliable base drive design for linear amplification
T_J(max)	150 °C - maximum junction temperature; enables operation in under-hood automotive environments
Package	TO-220 - industry-standard through-hole power package with metal tab for heatsink mounting

Pinout & Package

BD241A-A is housed in a TO-220 package with three leads: emitter (pin 1), base (pin 2), collector (pin 3). The metal tab is electrically connected to the collector and serves as the primary thermal path.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit node	Low-impedance return path; connects directly to ground or load return in common-emitter configurations
2 (Base)	Control input	Receives forward-biased drive current (I_B ≈ I_C/h_FE) to saturate or cut off the transistor
3 (Collector)	Current entry node	High-current input terminal; electrically tied to metal tab for direct heatsink coupling

Key Features

Feature	Design Value
Automotive qualification	Qualified per AEC-Q101 - validated for under-hood temperature cycling, humidity, and vibration stress
Planar "Base Island" structure	Enables high h_FE stability and low V_CE(sat) across production lots and temperature ranges
ECOPACK® packaging	Lead-free second-level interconnect compliant with JEDEC JESD97; RoHS and REACH compliant
Safe Operating Area (SOA)	Defined up to 150°C junction temperature - supports reliable operation in sustained overload conditions

Applications

Audio Power Amplifier

Automotive Relay Driver

Use Scenario: Output stage of Class AB audio amplifier delivering up to 20 W into 4 Ω loads.

IC Role / Device Role / Timing Role: NPN power switch providing current gain and low-distortion signal amplification.

Use Value: Low V_CE(sat) reduces crossover distortion and improves thermal efficiency at full output swing.

Use Scenario: Driving 12 V automotive relays (e.g., headlight, fan, fuel pump control) in body control modules.

IC Role / Device Role / Timing Role: High-current saturated switch interfacing microcontroller GPIO to inductive load.

Use Value: Verified 3 A continuous rating and 150°C T_J ensure reliability in engine bay ambient temperatures up to 105°C.

DC Motor Speed Control

Industrial Linear Regulator Pass Element

Use Scenario: PWM-driven H-bridge half-bridge leg controlling brushed DC motors in power seats or window lifts.

IC Role / Device Role / Timing Role: High-current switching element handling bidirectional motor current up to 3 A peak.

Use Value: SOA curve validated for 5 A pulsed current (t_p < 1 ms) supports short-circuit motor stall protection.

Use Scenario: Series pass transistor in adjustable 5–15 V, 2 A linear regulators for test equipment power supplies.

IC Role / Device Role / Timing Role: Voltage-controlled current source regulating output via base bias feedback loop.

Use Value: Stable h_FE ≥25 at I_C = 1 A ensures predictable regulation loop gain and thermal foldback response.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BD241C-A	V_CEO = 100 V (vs. 60 V); same package, h_FE and P_TOT	Supports higher bus voltages in industrial SMPS or UPS inverters	Select when system V_CC exceeds 60 V but thermal and gain requirements match BD241A-A
TIP31C	V_CEO = 100 V, I_C = 3 A, P_TOT = 40 W, but h_FE min = 10 @ I_C = 3 A (vs. 10 for BD241A-A at same condition)	Lower gain consistency at high current; less suitable for precision linear amplifiers	Acceptable for basic switching where gain variation is tolerable; verify SOA compliance for pulse loads

Compared with BD241C-A and TIP31C, BD241A-A offers optimal balance of automotive qualification, 60 V blocking, and guaranteed h_FE ≥25 at 1 A - making it preferred for cost-sensitive, thermally constrained audio and relay driver designs requiring AEC-Q101 validation.

Availability

BD241A-A is available at Aetrix Electronics and suitable for automotive body electronics, audio subsystems, and industrial relay control requiring stable component supply and long-term lifecycle support.

Supply support for BD241A-A 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, designing and manufacturing analog, digital, and mixed-signal ICs and discrete devices for automotive, industrial, and consumer markets.

BD241A-A belongs to ST's high-reliability bipolar power transistor product line, engineered specifically for automotive-grade linear amplification and switching applications demanding AEC-Q101 compliance and extended temperature operation.

FAQ

Is BD241A-A pin-compatible with BD241C-A?

Yes - both share identical TO-220 package footprint and pinout (E-B-C). However, BD241C-A has higher V_CEO (100 V vs. 60 V) and identical thermal and gain specs, allowing drop-in replacement only if system voltage remains within 60 V.

What is the maximum allowable case temperature for continuous 3 A operation?

At I_C = 3 A, the device must be mounted on a heatsink limiting T_case to ≤25°C to sustain full 40 W dissipation. Derating begins linearly above 25°C, reaching zero power at 150°C per the published derating curve.

Does BD241A-A require external base current limiting in switching applications?

Yes - base current must be limited to ≤1 A (absolute max) and sized to ensure saturation (I_B ≥ I_C/h_FE(min)). For I_C = 3 A, minimum recommended I_B is 0.3 A assuming h_FE ≥10, but 0.6 A is used in datasheet test conditions to guarantee V_CE(sat) ≤1.2 V.

Is BD241A-A still in active production?

No - STMicroelectronics lists BD241A-A as Obsolete Product(s) in the official datasheet revision history. Aetrix Electronics maintains legacy inventory with full traceability and provides last-time-buy support and cross-reference guidance for qualified replacements.

BD241A-A Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 1.2V @ 600mA, 3A

Current - Collector Cutoff (Max):: 300µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 25 @ 1A, 4V

Power - Max:: 40 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

BD241A-A FAQ

1.How can I place an order for BD241A-A through Aetrix?

Please submit a Request for Quotation (RFQ) for BD241A-A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BD241A-A reliable?

The price and inventory of BD241A-A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD241A-A is usually 5 days.

3.What payment methods are accepted for BD241A-A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD241A-A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD241A-A?

BD241A-A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD241A-A order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BD241A-A?

For technical support, including BD241A-A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD241A-A requirements.

6.How does Aetrix verify that BD241A-A is sourced from the original manufacturer or authorized distributors?

All BD241A-A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BD241A-A meets industry standards.

7.What is the process for return or replacement of BD241A-A?

All BD241A-A units undergo pre-shipment inspection (PSI). If there is an issue with BD241A-A, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BD241A-A part is unused and in its original packaging.

Return procedure for BD241A-A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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