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

STMicroelectronics BD911

Name: BD911
Brand: STMicroelectronics
SKU: BD911
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD911

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BD911.pdf

Description:: TRANS NPN 100V 15A TO-220

Quantity:: RFQ Add To RFQ list

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Inventory:1,360

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Product details

Overview

BD911 from STMicroelectronics is a silicon epitaxial-base NPN power transistor in TO-220 package, designed for high-current linear and switching applications such as audio output stages and DC-DC converter switches. It features V_CEO = 100 V, I_C = 15 A, P_tot = 90 W at T_c ≤ 25 °C, R_thj-case = 1.4 °C/W, and h_FE ≥ 5 at I_C = 10 A.

For engineers reviewing the BD911 datasheet, BD911 pinout, BD911 application, or BD911 equivalent, key selection criteria include safe operating area (SOA) compliance at 100 V/15 A, thermal derating behavior above 25 °C case temperature, saturation voltage under high-current switching (V_CE(sat) ≤ 3 V at I_C = 10 A), and complementary pairing with BD912 for push-pull amplifier designs.

Technical Context

The BD911 operates as a medium-power NPN bipolar junction transistor optimized for ruggedized linear amplification and hard-switching duty. Its epitaxial base structure supports stable h_FE across I_C = 0.5–10 A and enables reliable operation up to T_j = 150 °C with defined SOA boundaries.

It delivers V_CEO(sus) = 100 V under pulsed conditions (300 µs, 1.5% duty), V_CE(sat) = 1 V at I_C = 5 A / I_B = 0.5 A, and f_T = 3 MHz - confirming suitability for audio-frequency switching and low-MHz PWM control where gain-bandwidth trade-offs are critical.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	100 V - Maximum collector-emitter voltage before breakdown under open-base condition; defines upper rail limit in switch-mode topologies.
I_C	15 A - Continuous collector current rating at T_c ≤ 25 °C; sets peak load capability in Class-AB audio outputs.
P_tot	90 W - Total power dissipation at case temperature ≤ 25 °C; requires heatsink design supporting R_thj-amb < 1.78 °C/W for full-load operation.
R_thj-case	1.4 °C/W - Junction-to-case thermal resistance; determines minimum heatsink interface performance needed to maintain T_j ≤ 150 °C.
h_FE	5 (min) at I_C = 10 A - DC current gain at high current; informs base drive circuit sizing for saturated switching.
V_CE(sat)	3 V (max) at I_C = 10 A / I_B = 2.5 A - Saturation voltage defining conduction loss in switching applications.
f_T	3 MHz - Transition frequency at I_C = 0.5 A / V_CE = 4 V; indicates usable bandwidth for analog amplification or low-frequency PWM.

Pinout & Package

BD911 uses the standard JEDEC TO-220 plastic package with three leads: Collector (tab), Base (pin 1), Emitter (pin 2). The metal tab is electrically connected to the collector and must be insulated from heatsink unless referenced to system ground.

Pin/Terminal	Circuit Role	Design Meaning
Tab (Collector)	Main power output terminal	Electrically tied to collector; requires insulating washer when mounted to grounded heatsink.
Pin 1	Base	Current-controlled input node; requires driver capable of delivering ≥2.5 A peak base current for full saturation at 10 A collector load.
Pin 2	Emitter	Reference node for base-emitter biasing; typically connected to ground or low-side return path in common-emitter configurations.

Key Features

Feature	Design Value
High V_CEO rating	100 V enables use in 48 V industrial bus and 80 V automotive auxiliary systems without series stacking.
Low R_thj-case	1.4 °C/W allows compact heatsink integration in space-constrained power stages while maintaining thermal safety margin.
Guaranteed h_FE at high I_C	Minimum h_FE = 5 at I_C = 10 A ensures predictable base drive requirements in high-current switching circuits.
SOA-compliant construction	Defined Safe Operating Area curves support reliable operation under inductive load switching with controlled second breakdown limits.

Applications

Audio Power Amplifier Output Stage

DC-DC Converter Switch

Use Scenario: Final output stage in 50 W Class-AB audio amplifier driving 4 Ω or 8 Ω loudspeakers.

IC Role / Device Role / Timing Role: NPN power switch in complementary pair with BD912; handles positive half-cycle current delivery.

Use Value: V_CEO = 100 V and I_C = 15 A support headroom for transient peaks up to 70 W without clipping or thermal runaway.

Use Scenario: High-side switch in non-isolated buck converter supplying 12 V @ 8 A from 48 V input.

IC Role / Device Role / Timing Role: Main switching element operating at ≤100 kHz with forced base drive.

Use Value: V_CE(sat) ≤ 3 V at 10 A minimizes conduction loss (≤30 W), while SOA compliance prevents failure during startup inrush.

Motor Drive Half-Bridge

Linear Regulator Pass Element

Use Scenario: Low-side switch in brushed DC motor H-bridge controlling 24 V / 10 A permanent magnet motor.

IC Role / Device Role / Timing Role: Ground-referenced NPN switch enabling bidirectional current flow via complementary BD912 high-side control.

Use Value: h_FE ≥ 5 at 10 A ensures base drive remains feasible with discrete transistor drivers, avoiding gate-driver IC dependency.

Use Scenario: Series pass transistor in adjustable 0–30 V / 5 A linear bench power supply.

IC Role / Device Role / Timing Role: Voltage-controlled current source dissipating up to 90 W during worst-case dropout (40 V in / 10 V out @ 5 A).

Use Value: P_tot = 90 W and T_j(max) = 150 °C allow continuous operation with properly sized heatsink and thermal foldback protection.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ST BD911S	Same die, TO-220FP package with isolated tab; R_thj-case = 1.6 °C/W vs. 1.4 °C/W.	Eliminates need for insulating hardware in grounded heatsink layouts.	Select BD911S when mechanical isolation simplifies thermal mounting and layout.
ON Semiconductor MJE13009	V_CEO = 400 V, I_C = 12 A, P_tot = 100 W, h_FE = 8–40 at I_C = 5 A.	Better voltage margin but lower current gain consistency at high I_C.	Choose MJE13009 only if >100 V blocking is required; verify SOA fit for 10 A switching.

Compared with BD911S, the BD911 offers lower thermal resistance but requires electrical isolation; versus MJE13009, it trades higher voltage rating for tighter h_FE control and proven SOA in audio-grade linear operation.

Availability

BD911 is available at Aetrix Electronics and suitable for audio amplifier output stages, DC-DC converter switches, motor drive half-bridges, and linear regulator pass elements requiring stable component supply and long-term industrial availability.

Supply support for BD911 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 microcontrollers, power transistors, sensors, and analog ICs for industrial, automotive, and consumer markets.

The BD9xx series belongs to ST's legacy power bipolar transistor product line, engineered specifically for robust linear amplification and medium-frequency switching in cost-sensitive industrial power systems.

FAQ

Is BD911 pin-compatible with BD909?

Yes - BD911 and BD909 share identical TO-220 pinout (Collector-tab, Base-pin1, Emitter-pin2) and mechanical dimensions. However, BD911 has higher V_CEO (100 V vs. 80 V) and V_CBO ratings, making it a direct upgrade where increased voltage margin is needed without layout changes.

Can BD911 be used in parallel configurations?

Yes, but only with emitter resistors (0.1–0.22 Ω) to ensure current sharing. The BD911's positive temperature coefficient of V_CE(sat) supports inherent thermal balancing, but mismatched h_FE between units requires external ballasting for reliable multi-device operation above 20 A total current.

What is the maximum safe continuous collector current at 75 °C case temperature?

At T_c = 75 °C, derating begins at 90 W / 1.4 °C/W = 64.3 °C above ambient - so maximum allowable power drops to ~54 W. Using P = I² × R_CE(sat) approximation and typical V_CE(sat) ≈ 2 V, max continuous I_C is approximately 11.5 A, confirmed by SOA curve intersection at 75 °C.

Does BD911 require a flyback diode when switching inductive loads?

Yes - because BD911 lacks integrated clamp diodes, an external fast-recovery or Schottky diode (e.g., STTH1R06) must be placed across the inductive load to suppress V_L = −L·di/dt voltage spikes exceeding V_CEO, preventing secondary breakdown during turn-off.

BD911 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Active

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 15 A

Voltage - Collector Emitter Breakdown (Max):: 100 V

Vce Saturation (Max) @ Ib, Ic:: 3V @ 2.5A, 10A

Current - Collector Cutoff (Max):: 1mA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 15 @ 5A, 4V

Power - Max:: 90 W

Frequency - Transition:: 3MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

BD911 FAQ

1.How can I place an order for BD911 through Aetrix?

Please submit a Request for Quotation (RFQ) for BD911 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 BD911 reliable?

The price and inventory of BD911 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD911 is usually 5 days.

3.What payment methods are accepted for BD911?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD911 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD911?

BD911 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD911 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 BD911?

For technical support, including BD911 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD911 requirements.

6.How does Aetrix verify that BD911 is sourced from the original manufacturer or authorized distributors?

All BD911 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 BD911 meets industry standards.

7.What is the process for return or replacement of BD911?

All BD911 units undergo pre-shipment inspection (PSI). If there is an issue with BD911, 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 BD911 part is unused and in its original packaging.

Return procedure for BD911:

1.Submit a request within 90 days.

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

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