Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

onsemi BUT11

Name: BUT11
Brand: onsemi
SKU: BUT11
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: BUT11

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BUT11.pdf

Description:: TRANS NPN 400V 5A TO-220-3

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:4,566

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

BUT11 from ON Semiconductor is an NPN silicon power transistor in TO-220 package, rated for 400 V V_CEO, 5 A DC collector current, and 100 W collector dissipation at T_C = 25°C. It serves as a high-voltage switching device in offline power supplies and motor control circuits where ruggedness and pulse handling are critical.

For engineers reviewing the BUT11 datasheet, pinout, applications, or equivalent options, key selection criteria include its 400 V V_CEO, 1.5 V V_CE(sat) at 3 A/0.6 A drive, 1 µs turn-on time, and TO-220 thermal resistance of 1.25°C/W - all essential for reliable high-voltage switching design validation.

Technical Context

The BUT11 operates as a single NPN bipolar junction transistor optimized for high-voltage, medium-current switching. Its safe operating area (SOA) is defined up to 850 V V_CBO and 10 A pulsed collector current, with specified storage time (4 µs) and fall time (0.8 µs) enabling predictable commutation in inductive loads.

Designed for linear and switched-mode operation, it features a minimum h_FE of 10 at I_C = 3 A and V_CE = 5 V, and sustains 400 V in open-base configuration (V_CEO(sus)). Thermal derating begins at T_C > 25°C, following a linear 0.8 W/°C reduction from 100 W maximum.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	400 V - Maximum continuous collector-emitter voltage before breakdown under standard bias conditions
I_C (DC)	5 A - Sustained collector current capability without thermal runaway at T_C = 25°C
P_C	100 W - Maximum steady-state power dissipation at case temperature of 25°C
V_CE(sat)	1.5 V @ I_C = 3 A, I_B = 0.6 A - Low saturation voltage minimizes conduction loss in switching applications
t_ON	1 µs - Fast turn-on enables high-frequency switching up to ~100 kHz in hard-switched topologies
R_θjC	1.25 °C/W - Junction-to-case thermal resistance supports heatsink-based thermal management

Pinout & Package

Package: TO-220 (3-lead, straight lead, insulated tab). Mounting requires electrically isolated heatsink interface due to collector-connected tab.

Pin/Terminal	Circuit Role	Design Meaning
1 (Base)	Control input	Receives base current to drive transistor into saturation or cutoff; requires external current-limiting resistor
2 (Collector)	High-side power path	Connected to collector tab; electrically tied to metal mounting surface - must be insulated from heatsink
3 (Emitter)	Power return path	Serves as common emitter node; low-impedance connection to ground or load return in low-side switch configurations

Key Features

Feature	Design Value
High V_CBO rating	850 V - Enables use in 400 V AC mains-derived circuits with margin against transients and ringing
Pulsed current capability	10 A @ 300 µs / 1.5% duty cycle - Supports short-duration overload and inrush current handling
Low V_BE(sat)	1.3 V @ I_C = 3 A, I_B = 0.6 A - Reduces base drive power requirement and simplifies driver stage design
SOA compliance	Defined up to 800 V / 10 A boundary - Ensures safe operation during switching transitions with inductive loads

Applications

Switch-Mode Power Supply	AC Motor Starter
Use Scenario: Primary-side switching in 50–100 W offline flyback converters operating directly from 230 V AC mains. IC Role / Device Role / Timing Role: High-voltage NPN switch controlling energy transfer through transformer primary winding. Use Value: 400 V V_CEO and 100 W dissipation support continuous operation with margin over peak line voltage and reflected transients.	Use Scenario: Electromechanical contactor replacement in single-phase induction motor soft-start circuits. IC Role / Device Role / Timing Role: Medium-current, high-voltage switch enabling controlled ramp-up of motor voltage via phase-angle control. Use Value: 5 A DC rating and 4 µs storage time allow precise gate timing and reduced EMI during zero-crossing switching.
DC-DC Converter	Industrial Relay Driver
Use Scenario: Step-down converter in 24 V industrial rail systems driving solenoids or actuators requiring 12 V output. IC Role / Device Role / Timing Role: Main switching transistor in non-isolated buck topology with freewheeling diode. Use Value: 1.5 V V_CE(sat) limits conduction loss to <1.5 W at 3 A, improving efficiency and reducing heatsink size.	Use Scenario: Solid-state replacement for electromechanical relays controlling 120 V AC lighting or HVAC loads. IC Role / Device Role / Timing Role: High-voltage switching element interfacing microcontroller GPIO to AC load via optocoupler isolation. Use Value: 850 V V_CBO and SOA-defined safe operation ensure reliability across surge-prone building wiring environments.

Switch-Mode Power Supply

AC Motor Starter

Use Scenario: Primary-side switching in 50–100 W offline flyback converters operating directly from 230 V AC mains.

IC Role / Device Role / Timing Role: High-voltage NPN switch controlling energy transfer through transformer primary winding.

Use Value: 400 V V_CEO and 100 W dissipation support continuous operation with margin over peak line voltage and reflected transients.

Use Scenario: Electromechanical contactor replacement in single-phase induction motor soft-start circuits.

IC Role / Device Role / Timing Role: Medium-current, high-voltage switch enabling controlled ramp-up of motor voltage via phase-angle control.

Use Value: 5 A DC rating and 4 µs storage time allow precise gate timing and reduced EMI during zero-crossing switching.

DC-DC Converter

Industrial Relay Driver

Use Scenario: Step-down converter in 24 V industrial rail systems driving solenoids or actuators requiring 12 V output.

IC Role / Device Role / Timing Role: Main switching transistor in non-isolated buck topology with freewheeling diode.

Use Value: 1.5 V V_CE(sat) limits conduction loss to <1.5 W at 3 A, improving efficiency and reducing heatsink size.

Use Scenario: Solid-state replacement for electromechanical relays controlling 120 V AC lighting or HVAC loads.

IC Role / Device Role / Timing Role: High-voltage switching element interfacing microcontroller GPIO to AC load via optocoupler isolation.

Use Value: 850 V V_CBO and SOA-defined safe operation ensure reliability across surge-prone building wiring environments.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BUT11A	Higher V_CEO (450 V) and V_CBO (1000 V); otherwise identical pinout, package, and saturation characteristics	Preferred in 277 V AC or higher-input systems where additional voltage margin is required	Select BUT11A when operating near 400 V DC bus or subject to >100 V transient spikes
MJE13009	Lower V_CEO (400 V same), but higher I_C (12 A), lower V_CE(sat) (1.2 V), and TO-220F package with insulated tab	Better suited for higher-current, lower-loss designs where thermal interface simplicity is prioritized	Choose MJE13009 when board layout allows larger heatsink footprint and base drive can support higher I_B

Compared with BUT11A and MJE13009, the BUT11 offers balanced voltage rating and proven ruggedness for cost-sensitive 400 V-class switching, while BUT11A extends voltage headroom and MJE13009 improves current capacity and thermal interface convenience.

Availability

BUT11 is available at Aetrix Electronics and suitable for offline power supplies, AC motor starters, and industrial relay drivers requiring stable component supply and long-term manufacturability.

Supply support for BUT11 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 manufacturer specializing in power management, analog, sensor, and logic solutions for automotive, industrial, cloud, and consumer markets.

The BUT11 belongs to ON Semiconductor's legacy high-voltage bipolar transistor product line, originally developed by Fairchild Semiconductor for robust, discrete switching in mains-connected equipment.

FAQ

What is the maximum collector-emitter voltage rating for BUT11?

The BUT11 has a maximum collector-emitter voltage (V_CEO) rating of 400 V at T_C = 25°C. This value is confirmed in the Absolute Maximum Ratings table and applies under DC conditions with base open. Exceeding this voltage risks avalanche breakdown and permanent device failure. Designers should apply derating per application stress, especially in circuits with inductive kickback or line transients.

Does BUT11 have a built-in base-emitter resistor?

No, the BUT11 does not include any integrated base-emitter resistor. It is a standard three-terminal NPN bipolar transistor requiring external base drive circuitry - including current-limiting resistors and, optionally, a base-emitter shunt resistor for improved turn-off speed. The datasheet provides no internal resistor specifications, and all electrical characteristics assume discrete external biasing.

What is the thermal resistance from junction to case for BUT11?

The BUT11 has a typical junction-to-case thermal resistance (R_θjC) of 1.25°C/W, as specified in the Thermal Characteristics table. This value assumes proper mechanical mounting to a flat, smooth heatsink surface with recommended torque and thermal interface material. Actual thermal performance depends on heatsink design, mounting pressure, and ambient conditions.

Can BUT11 be used in linear amplifier applications?

The BUT11 is characterized and qualified for switching operation, not linear amplification. While its h_FE curve is provided, the Safe Operating Area (SOA) graph and lack of linear-mode derating curves indicate it is not optimized for Class-A or AB amplifier use. Continuous linear operation risks secondary breakdown due to localized hot-spot formation, especially above 10 W dissipation.

Is BUT11 pin-compatible with BUT11A?

Yes, the BUT11 and BUT11A share identical pinout (Base–Collector–Emitter), package (TO-220), and mechanical dimensions. They differ only in absolute maximum voltage ratings: BUT11A specifies 450 V V_CEO and 1000 V V_CBO, versus 400 V and 850 V for BUT11. No PCB layout change is needed when upgrading to BUT11A for enhanced voltage margin.

BUT11 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 5 A

Voltage - Collector Emitter Breakdown (Max):: 400 V

Vce Saturation (Max) @ Ib, Ic:: 1.5V @ 600mA, 3A

Current - Collector Cutoff (Max):: 1mA

DC Current Gain (hFE) (Min) @ Ic, Vce:: -

Power - Max:: 100 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220-3

BUT11 FAQ

1.How can I place an order for BUT11 through Aetrix?

Please submit a Request for Quotation (RFQ) for BUT11 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 BUT11 reliable?

The price and inventory of BUT11 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BUT11 is usually 5 days.

3.What payment methods are accepted for BUT11?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BUT11 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BUT11?

BUT11 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BUT11 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 BUT11?

For technical support, including BUT11 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BUT11 requirements.

6.How does Aetrix verify that BUT11 is sourced from the original manufacturer or authorized distributors?

All BUT11 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 BUT11 meets industry standards.

7.What is the process for return or replacement of BUT11?

All BUT11 units undergo pre-shipment inspection (PSI). If there is an issue with BUT11, 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 BUT11 part is unused and in its original packaging.

Return procedure for BUT11:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…