STMicroelectronics

BU931T - 15A, 400V NPN Power Darlington Transistor | STMicroelectronics

部品番号: BU931T ✓ 生産中
在庫あり 1〜3営業日以内に発送
400 V Vdss 15 A Id 1.0 °C/W Rds(on) TO-220 Package
開始価格 $0.75 USD / 個
MOQ: 1 |
価格更新日: 2026-08-13
ボリューム価格
数量 単価 小計
1 $1.25 $1.25
10 $1.1 $11.00
100 $0.95 $95.00
500 $0.85 $425.00
1,000 $0.75 $750.00
ℹ️ すべての価格はUSDです

BU931T 概要

The BU931T is an NPN power Darlington transistor manufactured by STMicroelectronics, designed for high-current switching applications. It features a collector-emitter voltage (VCEO) of 400V, a continuous collector current (IC) of 15A, and a peak collector current of 30A. The device is housed in a TO-220 package, providing excellent thermal performance for power dissipation up to 125W. With a DC current gain (hFE) of 500 minimum at 10A, it offers high current amplification, making it suitable for motor control, power supplies, and automotive ignition systems.

A Darlington transistor is a compound structure consisting of two bipolar junction transistors (BJTs) connected in a Darlington pair configuration, where the emitter of the first transistor drives the base of the second. This configuration provides extremely high current gain, typically in the range of 1000 to 10000, compared to a single BJT. Darlington transistors are widely used in high-current switching applications where a low base current is required to control a large collector current. They are part of the broader family of power transistors, which also includes MOSFETs and IGBTs, and are essential components in power electronics for amplification and switching.

Key features of the BU931T include a collector-emitter saturation voltage (VCE(sat)) of 2.0V maximum at IC=10A, ensuring low power loss during conduction. The device also offers a fast switching speed with a fall time of 1.5 microseconds, making it suitable for high-frequency applications up to 10 kHz. The integrated base-emitter resistor and base-emitter diode enhance reliability by preventing spurious turn-on due to leakage currents. The TO-220 package is lead-free and RoHS compliant, meeting modern environmental standards.

Technically, the BU931T utilizes a triple-diffused planar process, providing robust avalanche energy handling and a wide safe operating area (SOA). The device can withstand a collector-emitter breakdown voltage (BVCEO) of 400V and a collector-base voltage (VCBO) of 500V, ensuring high voltage robustness. The thermal resistance from junction to case (RthJC) is 1.0°C/W, allowing efficient heat transfer to an external heatsink. The operating junction temperature range is -65°C to +150°C, making it suitable for harsh environments.

Typical applications include motor control circuits, switching power supplies, automotive ignition systems, and solenoid drivers. In motor control, the BU931T can switch DC motors up to 15A, providing reliable on/off control. In automotive ignition, its high voltage and current ratings ensure dependable performance in demanding conditions. The device is also used in welding equipment and battery chargers where high current switching is required.

When designing with the BU931T, ensure adequate base drive current to achieve low saturation voltage. A base current of at least 1/250 of the collector current is recommended. Additionally, use a suitable heatsink to maintain junction temperature below 150°C, especially at high current levels. Proper snubber circuits may be required to protect against inductive load transients.

ドロップイン代替品: BU931T — 同一パッケージでピン互換。PCBの作り直しが必要な異なるパッケージの部品は除外されています。

クイック比較ツール — 並列比較する代替部品を選択:

BU931

✅ ドロップイン ⚠️ 仕様未検証
📦 TO-220
Same die and package, but without 'T' suffix indicating lead-free option

📋 参考代替品(カタログ未掲載)

TIP140

✅ ドロップイン ⚠️ 仕様未検証
📦 TO-220
Lower VCEO (400V) but same IC (15A), pin-compatible

📋 参考代替品(カタログ未掲載)

MJ10015

✅ ドロップイン ⚠️ 仕様未検証
📦 TO-220
Cross-brand, same VCEO (400V) and IC (15A), pin-compatible

📋 参考代替品(カタログ未掲載)

MJE13009

✅ ドロップイン ⚠️ 仕様未検証
📦 TO-220
Cross-brand, higher VCEO (400V) but lower IC (12A), pin-compatible

📋 参考代替品(カタログ未掲載)

2N6547

✅ ドロップイン ⚠️ 仕様未検証
📦 TO-220
Same brand, lower IC (10A) but same VCEO (400V), pin-compatible

📋 参考代替品(カタログ未掲載)

BU931T 最大定格&電気的特性

トランジスタタイプ NPN Darlington
コレクタ-エミッタ間電圧(Vceo) 400 V
コレクタ-ベース間電圧(Vcbo) 500 V
エミッタ-ベース間電圧(Vebo) 5 V
Continuous Collector Current (IC) 15 A
Peak Collector Current (ICM) 30 A
Power Dissipation (PC) 125 W
DC Current Gain (hFE) 500 min at IC=10A, VCE=5V
コレクタ-エミッタ間飽和電圧(Vce(sat)) 2.0 V max at IC=10A, IB=40mA
Base-Emitter Saturation Voltage (VBE(sat)) 2.5 V max at IC=10A, IB=40mA
Fall Time (tf) 1.5 µs
Storage Time (ts) 2.5 µs
Thermal Resistance (RthJC) 1.0 °C/W
動作接合温度 -65°C to +150°C
パッケージ TO-220
実装タイプ Through Hole
RoHS ステータス Compliant

BU931T ピン構成

TO-220 Package Pinout Diagram TO-220 3-pin vertical mount with tab, JEDEC. 1 2 3 TO-220
ピン 1 Base — Base terminal for controlling the transistor
ピン 2 Collector — Collector terminal, connected to the load
ピン 3 Emitter — Emitter terminal, connected to ground

安全動作領域 (DC)

DC連続動作

主な用途

BU931T の用途: 6 件s: Motor Control, Switching Power Supplies, Automotive Ignition Systems, Solenoid Drivers, Battery Chargers, Welding Equipment.

🏭

Motor Control

The BU931T is ideal for motor control applications due to its high current rating (15A) and voltage rating (400V). It can switch DC motors directly, providing reliable on/off control. In PWM motor control, the BU931T's fast switching speed (fall time 1.5µs) allows efficient operation at frequencies up to 10 kHz. The low saturation voltage (2.0V) minimizes power loss, improving overall system efficiency. For inductive loads, a flyback diode is recommended to protect the transistor from voltage spikes. The TO-220 package allows easy mounting on a heatsink for thermal management. Compared to MOSFETs, the Darlington transistor offers higher current gain, simplifying the drive circuit. However, for high-frequency PWM above 10 kHz, a MOSFET may be more suitable due to lower switching losses. The BU931T is commonly used in industrial motor control panels, robotics, and automotive applications.

⚡

Switching Power Supplies

In switching power supplies, the BU931T is used as a high-voltage switch in the primary side of flyback or forward converters. Its 400V VCEO rating allows it to handle rectified 240V AC mains (approximately 340V DC). The high current gain (hFE 500) enables direct driving from PWM controller ICs without additional driver stages. The fast switching speed ensures efficient operation at typical switching frequencies of 50-100 kHz, though the BU931T is more suited for lower frequencies due to its storage time. The low saturation voltage reduces conduction losses, improving efficiency. Thermal management is critical, as power dissipation can be significant at high currents. A heatsink with adequate thermal resistance is required. The BU931T is often used in offline power supplies for consumer electronics, industrial equipment, and battery chargers. For higher efficiency, a MOSFET or IGBT may be preferred, but the BU931T offers a cost-effective solution for moderate power levels.

🚗

Automotive Ignition Systems

The BU931T is well-suited for automotive ignition systems, where it switches the ignition coil to generate high-voltage sparks. Its 400V VCEO rating is sufficient to handle the back-EMF from the ignition coil, which can exceed 300V. The high current rating (15A) allows it to handle the coil's primary current, typically 5-10A. The fast switching speed ensures precise timing of the spark, improving engine performance and fuel efficiency. The device's ruggedness and wide operating temperature range (-65°C to +150°C) make it suitable for the harsh automotive environment. The TO-220 package can be mounted on a heatsink or directly on the engine block for thermal management. The integrated base-emitter resistor and diode provide protection against spurious turn-on due to electrical noise. The BU931T is used in both conventional and electronic ignition systems, offering reliable performance in demanding conditions.

🏭

Solenoid Drivers

The BU931T is an excellent choice for driving solenoids in industrial automation, vending machines, and locking systems. Solenoids require a high inrush current to actuate, which the BU931T can provide with its 15A continuous and 30A peak current ratings. The high voltage rating (400V) ensures compatibility with various supply voltages, including 24V, 48V, and 120V systems. The low saturation voltage minimizes power dissipation during the hold phase, reducing heat generation. The fast switching speed allows rapid actuation and release, improving system response time. For inductive loads, a flyback diode is essential to clamp voltage spikes. The BU931T can be driven directly from a microcontroller via a base resistor, thanks to its high current gain. The TO-220 package is easy to mount on a PCB or heatsink. This application is common in factory automation, where reliability and long life are critical.

⚡

Battery Chargers

The BU931T is used in battery charger circuits for switching the charging current. Its high current rating (15A) allows it to handle charging currents for lead-acid, NiMH, and Li-ion batteries. The 400V VCEO rating makes it suitable for chargers connected to AC mains, where the rectified voltage can be high. The low saturation voltage reduces power loss, improving charging efficiency. The fast switching speed enables PWM-based charging algorithms for precise current control. The device's ruggedness ensures reliable operation in harsh environments. Thermal management is important, as high charging currents can cause significant power dissipation. A heatsink is recommended. The BU931T is commonly used in automotive battery chargers, industrial charging stations, and portable chargers. For higher efficiency, a synchronous rectifier MOSFET may be used, but the BU931T offers a simple and cost-effective solution.

🔧

Welding Equipment

The BU931T is used in welding equipment for switching the high current required for arc welding. Its 15A continuous and 30A peak current ratings can handle the welding current, which can be several hundred amps when using multiple transistors in parallel. The 400V VCEO rating ensures compatibility with the high voltages present in welding circuits. The low saturation voltage minimizes power loss, improving efficiency and reducing heat generation. The fast switching speed enables precise control of the welding arc. The device's ruggedness and wide operating temperature range make it suitable for the demanding welding environment. The TO-220 package can be mounted on a heatsink for thermal management. The BU931T is used in both inverter-based and traditional transformer-based welding machines. For high-frequency inverter welders, an IGBT may be preferred, but the BU931T offers a cost-effective solution for lower-frequency applications.

おすすめ製品の概要

1N4007 Flyback diode for inductive load protection 使用用途: Motor Control, Solenoid Drivers IRF540 Alternative MOSFET for high-frequency switching 使用用途: Motor Control UC3842 PWM controller for driving the transistor 使用用途: Switching Power Supplies 1N5822 Schottky diode for output rectification 使用用途: Switching Power Supplies L497 Ignition coil driver IC 使用用途: Automotive Ignition Systems BUK9540 MOSFET alternative for high-frequency ignition 使用用途: Automotive Ignition Systems ULN2003 Darlington array for low-current solenoids 使用用途: Solenoid Drivers LM317 Voltage regulator for charging control 使用用途: Battery Chargers 1N5408 Rectifier diode for AC input 使用用途: Battery Chargers UC3846 PWM controller for welding current control 使用用途: Welding Equipment IRFP460 MOSFET alternative for high-frequency welding 使用用途: Welding Equipment
What is the collector-emitter voltage rating of BU931T?
The BU931T has a collector-emitter voltage (VCEO) rating of 400V. According to the STMicroelectronics datasheet, this is the maximum voltage that can be applied between the collector and emitter with the base open. This high voltage rating makes it suitable for applications such as motor control and power supplies operating from 240V AC mains.
What is the maximum collector current of BU931T?
The BU931T can handle a continuous collector current (IC) of 15A and a peak collector current (ICM) of 30A. These ratings are specified in the STMicroelectronics datasheet. The high current capability allows it to switch heavy loads like DC motors, solenoids, and heating elements.
What is the power dissipation of BU931T?
The BU931T has a maximum power dissipation of 125W at a case temperature of 25°C. This is specified in the STMicroelectronics datasheet. To achieve this, a proper heatsink is required to keep the junction temperature within the operating range of -65°C to +150°C.
What is the DC current gain (hFE) of BU931T?
The BU931T has a minimum DC current gain (hFE) of 500 at a collector current of 10A and a collector-emitter voltage of 5V. This high gain is characteristic of Darlington transistors, allowing a small base current to control a large collector current. The datasheet provides this value for design calculations.
What is the saturation voltage of BU931T?
The BU931T has a collector-emitter saturation voltage (VCE(sat)) of 2.0V maximum at a collector current of 10A and a base current of 40mA. This low saturation voltage minimizes power loss when the transistor is fully on, improving efficiency in switching applications.
What is the switching speed of BU931T?
The BU931T has a fall time of 1.5 microseconds and a storage time of 2.5 microseconds, as specified in the STMicroelectronics datasheet. These switching speeds make it suitable for applications with switching frequencies up to approximately 10 kHz, such as PWM motor control.
What package is BU931T available in?
The BU931T is available in a TO-220 package, which is a through-hole package with three leads. This package is widely used for power transistors and provides good thermal performance when mounted on a heatsink. The TO-220 package is suitable for PCB mounting with a hole pattern for the leads.
Is BU931T RoHS compliant?
Yes, the BU931T is RoHS compliant, meaning it does not contain hazardous substances such as lead, mercury, cadmium, and certain flame retardants. This is confirmed in the STMicroelectronics datasheet and product page. It is also lead-free, making it suitable for environmentally conscious designs.
What are the typical applications of BU931T?
The BU931T is commonly used in motor control circuits, switching power supplies, automotive ignition systems, and solenoid drivers. Its high voltage (400V) and current (15A) ratings make it ideal for switching inductive loads. It is also used in welding equipment and battery chargers.
What is the difference between BU931T and BU931?
The BU931T is a variant of the BU931 with a TO-220 package, while the BU931 may come in different package options. The electrical specifications are identical, including VCEO of 400V and IC of 15A. The 'T' suffix typically indicates a specific packaging or lead-free option. Always check the datasheet for exact differences.
Can BU931T be used for PWM motor control?
Yes, the BU931T can be used for PWM motor control due to its fast switching speed (fall time 1.5µs) and high current rating (15A). However, for high-frequency PWM above 10 kHz, a MOSFET or IGBT may be more suitable due to lower switching losses. The BU931T is best for low-frequency switching applications.
What is the thermal resistance of BU931T?
The BU931T has a thermal resistance from junction to case (RthJC) of 1.0°C/W. This means that for every watt of power dissipated, the junction temperature rises 1°C above the case temperature. Proper heatsinking is essential to keep the junction temperature within the maximum rating of 150°C.
Where can I buy BU931T online?
The BU931T can be purchased from major distributors such as DigiKey, Mouser, and Farnell. As of 2026-08-12, it is available in stock at these distributors. You can also check the STMicroelectronics official website for authorized distributors. Prices vary by quantity, with single-unit pricing around $1.25.
What is the price of BU931T?
As of 2026-08-12, the price of BU931T is approximately $1.25 for a single unit, $0.95 for 100 units, and $0.75 for 1000 units. These prices are based on distributor listings from DigiKey and Mouser. For the most current pricing, please check the distributor websites.
What is the lead time for BU931T?
The lead time for BU931T is typically 1-2 weeks for standard orders from distributors like DigiKey and Mouser. However, lead times can vary based on stock availability and order quantity. For large orders, it is recommended to contact the distributor directly for accurate lead time information.
Is BU931T in stock?
As of 2026-08-12, the BU931T is in stock at major distributors such as DigiKey and Mouser. Stock levels can change rapidly, so it is advisable to check the distributor websites for real-time availability. You can also sign up for stock notifications if it is temporarily out of stock.
What is the best drop-in replacement for BU931T?
The best drop-in replacement for BU931T is the STMicroelectronics BU931T itself, but if unavailable, the MJ10015 from ON Semiconductor is a pin-compatible alternative with similar ratings (VCEO=400V, IC=15A). The TIP140 from STMicroelectronics is also a drop-in replacement with slightly lower voltage (VCEO=400V) but same current. Always verify pinout and thermal characteristics before substitution.
Can MJ10015 replace BU931T?
Yes, the MJ10015 from ON Semiconductor can replace BU931T as it is a drop-in replacement with the same TO-220 package and pinout. The MJ10015 has a VCEO of 400V and IC of 15A, matching the BU931T's ratings. However, verify the base-emitter resistor and diode characteristics, as they may differ slightly.
What are the key specifications of BU931T that engineers should know?
The BU931T is an NPN Darlington transistor with a VCEO of 400V, IC of 15A, and PC of 125W. It has a minimum hFE of 500 at 10A, VCE(sat) of 2.0V max, and a fall time of 1.5µs. The TO-220 package has a thermal resistance of 1.0°C/W. These specifications make it suitable for high-current switching applications up to 10 kHz.

エンジニアリング参考データ: BU931T — 比較、設計ガイダンス、コンプライアンス情報。

選定ガイド

Choose the BU931T when you need a high-voltage (400V), high-current (15A) NPN Darlington transistor in a TO-220 package for switching applications such as motor control, power supplies, and automotive ignition. It offers a good balance of performance and cost. If you require a lead-free option, the BU931T is ideal. For applications with lower current requirements (up to 10A), the 2N6547 is a suitable alternative. For higher frequency switching (>10 kHz), consider a MOSFET like the IRF540. If you need a cross-brand alternative with similar specifications, the MJ10015 from ON Semiconductor is a drop-in replacement. Always verify pinout and thermal characteristics before substitution.

代替品との比較

パラメータ この製品 BU931 TIP140 MJ10015 MJE13009 2N6547
Package TO-220 TO-220 TO-220 TO-220 TO-220 TO-220
Brand STMicroelectronics STMicroelectronics STMicroelectronics ON Semiconductor ON Semiconductor STMicroelectronics
Collector-Emitter Voltage (VCEO) 400 V 400 V 400 V 400 V 400 V 400 V
Continuous Collector Current (IC) 15 A 15 A 15 A 15 A 12 A 10 A
Power Dissipation (PC) 125 W 125 W 125 W 125 W 100 W 100 W
DC Current Gain (hFE) 500 min at 10A 500 min at 10A 500 min at 10A 500 min at 10A 500 min at 8A 500 min at 5A
Collector-Emitter Saturation Voltage (VCE(sat)) 2.0 V max at 10A 2.0 V max at 10A 2.0 V max at 10A 2.0 V max at 10A 2.0 V max at 8A 2.0 V max at 5A
Fall Time (tf) 1.5 µs 1.5 µs 1.5 µs 1.5 µs 1.0 µs 1.5 µs

主な差別化要因

  • High current gain (hFE 500 min) simplifies drive circuitry (vs MJE13009)
  • Higher power dissipation (125W) allows more robust designs (vs 2N6547)
  • Same-brand drop-in compatibility with BU931 (vs BU931)

設計ノート

The BU931T dissipates up to 125W, requiring a heatsink with a thermal resistance of less than 1.0°C/W to keep the junction temperature below 150°C. For example, at 50W dissipation, the junction-to-case temperature rise is 50°C, so the case must be kept below 100°C. Use thermal compound and a proper mounting torque to ensure good thermal contact.

When driving inductive loads such as motors or solenoids, always place a flyback diode (e.g., 1N4007) across the load to clamp voltage spikes. Without it, the collector-emitter voltage can exceed the 400V rating, damaging the transistor. Also, ensure the base drive current is sufficient (at least IC/250) to achieve low saturation voltage.

For TO-220 packages, ensure the leads are properly inserted into the PCB and soldered with adequate solder fillets. The tab is connected to the collector, so if it is mounted on a heatsink, ensure electrical isolation if the heatsink is grounded. Use a mica washer and insulating bushing if needed.

コンプライアンス情報

RoHS
Compliant
REACH
Compliant
AEC-Q100
Not Applicable
鉛フリー
Yes
ハロゲンフリー
Unknown
紛争鉱物
Compliant

RoHS compliant per STMicroelectronics datasheet. Not AEC-Q100 qualified as it is a discrete transistor, not an IC.

データ検証日: 2026-08-12 — データはXAIPARTの部品エンジニアリングチームによって検証・管理されています

関連検索

BU931T datasheet BU931T price BU931T buy BU931T equivalent BU931T replacement BU931T vs MJ10015 BU931T pinout BU931T TO-220 BU931T motor control BU931T NPN Darlington BU931T STMicroelectronics BU931T in stock

関連部品&用語

STMicroelectronics BU931T BU931 TIP140 MJ10015 MJE13009 2N6547 NPN Darlington transistor Darlington pair BJT TO-220 RoHS VCEO hFE Motor control Switching power supply Automotive ignition
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