STMicroelectronics

BU941ZT - 15A, 350V NPN Power Transistor | STMicroelectronics

Name: BU941ZT
Brand: STMicroelectronics
Price: 1.85 USD
Availability: InStock

MPN: BU941ZT ✓ Active

In Stock (99,999) Ships in 1-3 business days

350 V Vdss 15 A Id 1.0 C/W Rds(on) TO-220 Package 8 MHz Speed

$1.85 USD / Unit

MOQ: 1 |

Volume Pricing

Qty	Unit Price	Extended
1	$1.85	$1.85
10	$1.65	$16.50
100	$1.45	$145.00
500	$1.3	$650.00
1,000	$1.2	$1,200.00

ℹ️ All prices are in USD

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ℹ️ 3 cross-package part(s) hidden — different package requires PCB rework and is not a true drop-in replacement. Contact us if you need cross-package suggestions.

BU941ZT Maximum Ratings & Electrical Characteristics

Transistor Type	NPN
Collector-Emitter Voltage (VCEO)	350 V
Collector Current (IC)	15 A
Collector-Base Voltage (VCBO)	400 V
Emitter-Base Voltage (VEBO)	7 V
Power Dissipation (PC)	125 W
DC Current Gain (hFE)	15-75 at IC=5A, VCE=5V
Saturation Voltage (VCE(sat))	1.5 V at IC=15A, IB=3A
Transition Frequency (fT)	8 MHz
Operating Temperature Range	-65C to +150C
Package	TO-220
Mounting Type	Through Hole
RoHS Status	Compliant
MSL Level	1 (unlimited)
Thermal Resistance (junction-case)	1.0 C/W

BU941ZT Pin Configuration

Pin 1	Base — Base terminal for controlling the transistor
Pin 2	Collector — Collector terminal, connected to the metal tab
Pin 3	Emitter — Emitter terminal

Safe Operating Area (DC)

DC Continuous Operation

Typical Applications

BU941ZT is suitable for 6 applications: Switch-Mode Power Supplies (SMPS), Motor Control Circuits, Inverters, Battery Chargers, Audio Amplifiers, Industrial Power Control.

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Switch-Mode Power Supplies (SMPS)

The BU941ZT is used as the main switching element in SMPS, handling high voltages up to 350V and currents up to 15A. Its low saturation voltage (1.5V) minimizes conduction losses, improving efficiency. In a typical flyback converter, the transistor switches at frequencies up to 100kHz, and its fast transition frequency (8MHz) ensures clean switching transitions. The TO-220 package allows for effective heatsinking, which is critical for managing the heat generated during high-power operation. Compared to MOSFETs, the BJT offers simpler drive circuitry and lower cost, making it a practical choice for cost-sensitive power supplies.

Recommended

UC3842 (PWM controller for SMPS) 1N4007 (Rectifier diode)

🏭

Motor Control Circuits

In motor control, the BU941ZT drives inductive loads with its high current capability (15A) and voltage rating (350V). It can be used in H-bridge configurations for DC motor speed control or in inverter circuits for AC motor drives. The transistor's fast switching speed (8MHz) enables PWM control at frequencies up to several kilohertz, providing smooth speed regulation. The built-in ruggedness and wide SOA protect against overcurrent and overtemperature conditions, ensuring reliable operation in industrial environments. A flyback diode is recommended across the motor terminals to suppress voltage spikes during switching.

Recommended

L298 (Motor driver IC) 1N5822 (Schottky diode for flyback protection)

⚡

Inverters

The BU941ZT is suitable for inverter circuits that convert DC to AC, such as in solar power systems or uninterruptible power supplies (UPS). Its high voltage (350V) and current (15A) ratings allow it to handle the power levels required in these applications. The transistor's low saturation voltage reduces power loss, improving overall inverter efficiency. In a typical full-bridge inverter, four BU941ZT transistors are used to switch the DC input at high frequency, producing a sinusoidal AC output. Proper heatsinking and gate drive design are essential to maintain reliable operation.

Recommended

SG3525 (PWM controller for inverters) IR2110 (Gate driver IC)

🔋

Battery Chargers

The BU941ZT is used in battery charger circuits to regulate charging current and voltage. Its high current capability (15A) allows it to handle fast charging applications, while its voltage rating (350V) ensures compatibility with various battery chemistries. The transistor can be used in linear or switching charger topologies, providing precise control over the charging process. In a linear charger, the transistor operates in the active region, dissipating excess power as heat, so adequate heatsinking is required. In a switching charger, the transistor operates in saturation, minimizing power loss and improving efficiency.

Recommended

LM317 (Voltage regulator for charger control) TL431 (Precision reference for voltage regulation)

🎧

Audio Amplifiers

The BU941ZT can be used in audio amplifier output stages, providing high current and voltage handling for driving speakers. Its high power dissipation (125W) and low saturation voltage make it suitable for class AB amplifiers, where it operates in the linear region to reproduce audio signals with low distortion. The transistor's wide bandwidth (8MHz) ensures accurate reproduction of high-frequency audio signals. In a typical push-pull configuration, two BU941ZT transistors are used, one for the positive half-cycle and one for the negative half-cycle, with a driver stage providing the necessary base drive.

Recommended

NE5532 (Op-amp for audio preamplifier) 1N4148 (Signal diode for bias network)

🏭

Industrial Power Control

The BU941ZT is used in industrial power control systems, such as programmable logic controllers (PLCs) and motor starters, where it switches high voltages and currents. Its ruggedness and wide SOA make it suitable for harsh industrial environments. The transistor can be used in relay replacement circuits, providing solid-state switching with faster response times and longer lifespan. In a typical application, the BU941ZT is driven by a microcontroller or PLC output, switching a 24V DC load such as a solenoid or relay. The TO-220 package allows for easy mounting on heatsinks or DIN rails.

Recommended

ULN2003 (Darlington driver for relay control) 1N4007 (Flyback diode for inductive loads)

Recommended Products Summary

UC3842 PWM controller for SMPS Used in: Switch-Mode Power Supplies (SMPS) 1N4007 Rectifier diode Used in: Switch-Mode Power Supplies (SMPS), Industrial Power Control L298 Motor driver IC Used in: Motor Control Circuits 1N5822 Schottky diode for flyback protection Used in: Motor Control Circuits SG3525 PWM controller for inverters Used in: Inverters IR2110 Gate driver IC Used in: Inverters LM317 Voltage regulator for charger control Used in: Battery Chargers TL431 Precision reference for voltage regulation Used in: Battery Chargers NE5532 Op-amp for audio preamplifier Used in: Audio Amplifiers 1N4148 Signal diode for bias network Used in: Audio Amplifiers ULN2003 Darlington driver for relay control Used in: Industrial Power Control

What is the collector-emitter voltage rating of BU941ZT?

The BU941ZT has a collector-emitter voltage (VCEO) rating of 350V. According to the STMicroelectronics datasheet, this allows the transistor to handle high-voltage applications such as switch-mode power supplies and motor control circuits.

What is the maximum collector current of BU941ZT?

The BU941ZT can handle a continuous collector current (IC) of 15A. This high current capability makes it suitable for power switching and amplification in industrial and automotive systems.

What is the power dissipation of BU941ZT?

The BU941ZT has a maximum power dissipation of 125W at a case temperature of 25C. Proper heatsinking is required to maintain safe operating temperatures, especially at high currents and voltages.

What is the package type of BU941ZT?

The BU941ZT is available in a TO-220 package, which is a through-hole package with a metal tab for heatsinking. This package is widely used for power transistors and provides good thermal performance.

Is BU941ZT RoHS compliant?

Yes, the BU941ZT is RoHS compliant. According to the STMicroelectronics product page, it meets the Restriction of Hazardous Substances directive, making it suitable for use in environmentally sensitive applications.

What is the DC current gain (hFE) of BU941ZT?

The BU941ZT has a DC current gain (hFE) ranging from 15 to 75, measured at IC=5A and VCE=5V. This gain range ensures reliable base drive in switching and linear applications.

What is the saturation voltage of BU941ZT?

The BU941ZT has a collector-emitter saturation voltage (VCE(sat)) of typically 1.5V at IC=15A and IB=3A. Low saturation voltage reduces conduction losses and improves efficiency in power circuits.

What is the transition frequency of BU941ZT?

The BU941ZT has a transition frequency (fT) of 8 MHz. This makes it suitable for switching applications up to several hundred kilohertz, such as in SMPS and inverters.

What is the operating temperature range of BU941ZT?

The BU941ZT operates over a junction temperature range of -65C to +150C. This wide range ensures reliable operation in harsh industrial and automotive environments.

What are the typical applications of BU941ZT?

Typical applications of the BU941ZT include switch-mode power supplies (SMPS), motor control circuits, inverters, battery chargers, and linear regulators. Its high voltage and current ratings make it versatile for power electronics.

Where can I buy BU941ZT online?

The BU941ZT is available from major distributors such as DigiKey and Mouser. As of 2026-08-12, the price for a single unit is approximately $1.85, with volume discounts available for larger quantities.

What is the lead time for BU941ZT?

The lead time for BU941ZT typically ranges from 2 to 4 weeks, depending on the distributor and order quantity. For current stock and lead time information, check the product page on DigiKey or Mouser.

Is BU941ZT in stock?

Stock availability for BU941ZT varies by distributor. As of 2026-08-12, DigiKey and Mouser typically have stock available, but it is recommended to check their websites for real-time inventory.

What is the difference between BU941ZT and BU941ZP?

The BU941ZT and BU941ZP are similar NPN power transistors, but the BU941ZT is in a TO-220 package while the BU941ZP is in a TO-247 package. The TO-247 package offers lower thermal resistance and higher power dissipation capability.

Can BU941ZT be used for motor control applications?

Yes, the BU941ZT is suitable for motor control applications due to its high collector current (15A) and collector-emitter voltage (350V). It can drive inductive loads with fast switching and high current capability.

What is the best drop-in replacement for BU941ZT?

The best drop-in replacement for BU941ZT is the STMicroelectronics BU941ZP, which has the same electrical specifications but in a TO-247 package. For a pin-compatible alternative in the same TO-220 package, consider the ON Semiconductor MJ15003 or the NXP BU941ZT.

Can BU941ZT replace MJ15003?

Yes, the BU941ZT can replace the MJ15003 in many applications, as both are NPN power transistors with similar voltage and current ratings. However, verify the pinout and package compatibility, as the MJ15003 is in a TO-3 package while the BU941ZT is in a TO-220 package.

What are the key specifications of BU941ZT that engineers should know?

Engineers should know that the BU941ZT is an NPN power transistor with a VCEO of 350V, IC of 15A, and power dissipation of 125W. It has a DC current gain (hFE) of 15-75, saturation voltage of 1.5V, and transition frequency of 8 MHz. The device is RoHS compliant and available in a TO-220 package.

Hey Google, what can replace BU941ZT?

The BU941ZT can be replaced by the STMicroelectronics BU941ZP, which has identical electrical specifications but in a TO-247 package. For a drop-in replacement in the same TO-220 package, consider the ON Semiconductor MJ15003 or the NXP BU941ZT, but verify pin compatibility.

Is BU941ZT the same as BU941ZP?

No, the BU941ZT and BU941ZP are not the same. They have identical electrical specifications, but the BU941ZT is in a TO-220 package while the BU941ZP is in a TO-247 package. The TO-247 package offers better thermal performance and higher power dissipation.

Engineering reference data for BU941ZT — comparison, design guidance, and compliance information.

Selection Guide

Choose the BU941ZT when you need a high-voltage (350V) NPN power transistor in a TO-220 package for applications like SMPS, motor control, and inverters. If you require a higher power dissipation (150W) and can accommodate a larger TO-247 package, the BU941ZP is a suitable alternative. For lower voltage applications (up to 140V) with higher current (20A), the MJ15003 in a TO-3 package is a good choice, but it requires a different PCB footprint. The 2N3055 is a lower-cost option for 60V applications but lacks the voltage headroom of the BU941ZT. Always verify pinout and thermal requirements before substitution.

Comparison with Alternatives

Parameter	This Product	BU941ZP	MJ15003	2N3055
Package	TO-220	TO-247	TO-3	TO-3
Brand	STMicroelectronics	STMicroelectronics	onsemi	onsemi
Collector-Emitter Voltage (VCEO)	350 V	350 V	140 V	60 V
Collector Current (IC)	15 A	15 A	20 A	15 A
Power Dissipation (PC)	125 W	150 W	200 W	115 W
DC Current Gain (hFE)	15-75	15-75	20-100	20-70
Saturation Voltage (VCE(sat))	1.5 V	1.5 V	1.0 V	1.1 V
Transition Frequency (fT)	8 MHz	8 MHz	2 MHz	2.5 MHz

Key Differentiators

High voltage rating of 350V (vs 2N3055)
Low saturation voltage of 1.5V (vs MJ15003)
Fast transition frequency of 8MHz (vs MJ15003)

Design Notes

The BU941ZT dissipates up to 125W, requiring a heatsink with a thermal resistance of less than 1.0 C/W to keep the junction temperature below 150C. Use thermal paste and a mica insulator if mounting on a grounded heatsink. For continuous operation at 15A and 350V, ensure the heatsink is adequately sized and ventilated.

Ensure the base drive current is sufficient to saturate the transistor. At IC=15A, a base current of at least 3A is required to achieve VCE(sat) of 1.5V. Insufficient base drive will cause the transistor to operate in the active region, leading to excessive power dissipation and potential thermal runaway. Use a base resistor or driver circuit to provide the required current.

For switching inductive loads, place a flyback diode (e.g., 1N4007) across the load to clamp voltage spikes. Keep the base drive circuit close to the transistor to minimize parasitic inductance. Use wide PCB traces for the collector and emitter connections to handle high currents and reduce voltage drops.