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

STMicroelectronics BUB941ZTT4

Name: BUB941ZTT4
Brand: STMicroelectronics
SKU: BUB941ZTT4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: BUB941ZTT4

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-263-3, D2PAK (2 Leads + Tab), TO-263AB

Datasheet:: BUB941ZTT4.pdf

Description:: TRANS NPN DARL 350V 15A D2PAK

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:1,726

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

Product details

Overview

BUB941ZTT4 from STMicroelectronics is a high-voltage NPN power Darlington transistor designed for electronic ignition coil driving, featuring built-in clamping Zener (V_CL = 350–500 V), 350 V V_CEO, 15 A continuous collector current, and 175 °C maximum junction temperature in D2PAK (TO-263) surface-mount package.

For engineers reviewing the BUB941ZTT4 datasheet, BUB941ZTT4 pinout, BUB941ZTT4 application, or BUB941ZTT4 equivalent, this device is selected for rugged inductive switching in automotive ignition systems where high-voltage clamping, thermal robustness, and fast turn-off (t_s = 15 µs) are critical design requirements.

Technical Context

This Darlington pair integrates a main NPN output transistor with a driver stage and an internal Zener diode across C–E to clamp inductive kickback during coil de-energization. It operates with base-emitter saturation voltage of 2.2–2.5 V at 8–10 A, enabling direct drive from low-voltage logic-level controllers.

The device supports pulsed operation up to 30 A peak collector current (I_CM) and exhibits DC current gain (h_FE) ≥300 at I_C = 5 A, V_CE = 10 V - optimized for high-current, low-duty-cycle ignition pulse delivery.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	350 V - withstands ignition coil back-EMF without external snubber
I_C (continuous)	15 A - sustains full primary coil current in 12 V/24 V automotive systems
V_CL	350–500 V - clamps inductive voltage spike to protect downstream circuitry
T_j(max)	175 °C - enables reliable operation under under-hood thermal stress
R_thj-case	1.0 °C/W - low thermal resistance in D2PAK package supports high-power dissipation
t_s	15 µs - storage time limits switch-off delay in high-repetition ignition cycles
h_FE	≥300 @ I_C=5 A - reduces required base drive current for efficient control

Pinout & Package

D2PAK (TO-263) surface-mount package with exposed drain-connected tab for thermal and electrical grounding. Pin 1 = Base, Pin 2 = Collector (tab), Pin 3 = Emitter.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Base	Control input requiring ~100–250 mA drive to saturate at 8–10 A output
Pin 2	Collector (Tab)	Main high-current path; electrically and thermally connected to PCB copper pour
Pin 3	Emitter	Return path for load current; referenced to ground in low-side switch configuration

Key Features

Feature	Design Value
Integrated clamping Zener	Eliminates need for external transient voltage suppressor in ignition coil interface
High T_j rating (175 °C)	Permits operation in engine bay environments without derating below 15 A
D2PAK thermal performance	1.0 °C/W R_thj-case enables >100 W dissipation with moderate heatsinking
Low V_CE(sat)	1.8 V @ 8 A/100 mA base drive minimizes conduction loss and self-heating

Applications

Automotive Ignition Coils

Industrial Ignition Systems

Use Scenario: Driving primary winding of distributorless ignition system (DIS) coils in gasoline engines.

IC Role / Device Role / Timing Role: Low-side switch controlling coil energization/de-energization timing with precise dwell control.

Use Value: Built-in 350–500 V clamping prevents MOSFET or controller failure during high-dV/dt coil collapse.

Use Scenario: Triggering spark generation in gas-fired industrial burners and furnace igniters.

IC Role / Device Role / Timing Role: High-current Darlington switch delivering repetitive 10–15 A pulses to ignition transformer primaries.

Use Value: 175 °C T_j(max) and 15 A rating ensure reliability in unventilated control enclosures.

Motorcycle CDI Units

Aftermarket Ignition Modules

Use Scenario: Compact capacitive discharge ignition (CDI) modules for two-stroke and four-stroke motorcycles.

IC Role / Device Role / Timing Role: Final-stage power switch discharging capacitor bank into ignition coil primary.

Use Value: 30 A peak current capability handles high-energy CDI pulse demands without secondary breakdown.

Use Scenario: Retrofit electronic ignition kits replacing mechanical points in classic vehicles.

IC Role / Device Role / Timing Role: Solid-state replacement for breaker points, triggered by Hall or reluctor sensors.

Use Value: D2PAK surface-mount package allows compact, vibration-resistant PCB mounting in tight engine compartments.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage Darlington ignition switch applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BU941ZT	TO-220 through-hole package; R_thj-case = 1.0 °C/W (same); no tape-and-reel option	Requires wave soldering or socket mounting; less suitable for automated SMT lines	Select when manual assembly or legacy board layout mandates through-hole footprint
STGD10NB60KD	600 V, 10 A N-channel MOSFET; no integrated Zener; requires external TVS/clamp	Higher switching speed but needs gate driver and protection network	Select when faster switching (>100 kHz) and lower gate charge are prioritized over integration simplicity

Compared with BU941ZT and STGD10NB60KD, BUB941ZTT4 uniquely combines D2PAK SMT compatibility, integrated clamping, and proven ruggedness for cost-sensitive, thermally demanding ignition applications - eliminating both external protection components and through-hole assembly steps.

Availability

BUB941ZTT4 is available at Aetrix Electronics and suitable for automotive ignition modules, industrial burner controls, motorcycle CDI units, and aftermarket electronic ignition systems requiring stable component supply across production lifecycles.

Supply support for BUB941ZTT4 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, power, microcontroller, and sensor solutions for automotive, industrial, and consumer markets.

The BUB941ZTT4 belongs to ST's high-voltage bipolar power transistor family, engineered specifically for robust inductive load switching in harsh automotive and industrial environments.

FAQ

What is the recommended gate/base drive for BUB941ZTT4 in ignition applications?

Drive the base with 100–250 mA peak current using a logic-level compatible driver (e.g., ULN2003 or discrete transistor stage). A 47 Ω base resistor is typical for 5 V TTL/CMOS control. Avoid exceeding 5 A peak base current (I_BM) to prevent bond wire damage.

Can BUB941ZTT4 replace BU941ZT in existing TO-220 designs?

No direct footprint replacement: BUB941ZTT4 uses D2PAK (TO-263), while BU941ZT uses TO-220. PCB redesign is required. Thermal performance is equivalent (R_thj-case = 1.0 °C/W), but soldering process and mechanical mounting differ significantly.

Does BUB941ZTT4 require an external flyback diode?

No. The integrated Zener diode provides clamping across collector–emitter (V_CL = 350–500 V), eliminating the need for an external flyback diode in standard ignition coil applications per ST's functional test circuit (Fig. 1).

What is the safe operating area (SOA) limitation at 100 °C case temperature?

At T_c = 100 °C, maximum continuous collector current drops to ~10.5 A due to thermal derating (P_tot = 150 W × (1 − (100−25)/150) ≈ 105 W; I_C ≤ √(P_tot/R_CE(sat))). Pulse operation up to 30 A remains valid within 300 µs/1.5% duty cycle limits.

BUB941ZTT4 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-263-3, D2PAK (2 Leads + Tab), TO-263AB

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: NPN - Darlington

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

Voltage - Collector Emitter Breakdown (Max):: 350 V

Vce Saturation (Max) @ Ib, Ic:: 1.8V @ 250mA, 10A

Current - Collector Cutoff (Max):: 100µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 300 @ 5A, 10V

Power - Max:: 150 W

Frequency - Transition:: -

Operating Temperature:: 175°C (TJ)

Grade:: Automotive

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: D2PAK

BUB941ZTT4 FAQ

1.How can I place an order for BUB941ZTT4 through Aetrix?

Please submit a Request for Quotation (RFQ) for BUB941ZTT4 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 BUB941ZTT4 reliable?

The price and inventory of BUB941ZTT4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BUB941ZTT4 is usually 5 days.

3.What payment methods are accepted for BUB941ZTT4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BUB941ZTT4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BUB941ZTT4?

BUB941ZTT4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BUB941ZTT4 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 BUB941ZTT4?

For technical support, including BUB941ZTT4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BUB941ZTT4 requirements.

6.How does Aetrix verify that BUB941ZTT4 is sourced from the original manufacturer or authorized distributors?

All BUB941ZTT4 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 BUB941ZTT4 meets industry standards.

7.What is the process for return or replacement of BUB941ZTT4?

All BUB941ZTT4 units undergo pre-shipment inspection (PSI). If there is an issue with BUB941ZTT4, 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 BUB941ZTT4 part is unused and in its original packaging.

Return procedure for BUB941ZTT4:

1.Submit a request within 90 days.

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

Tech Hub

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…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…