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 KSE5741TU

Name: KSE5741TU
Brand: onsemi
SKU: KSE5741TU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: KSE5741TU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: KSE5741TU.pdf

Description:: TRANS NPN DARL 350V 8A TO-220-3

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:8,373

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

Product details

Overview

KSE5741TU from Fairchild Semiconductor is an NPN silicon Darlington transistor designed for high-voltage power switching in inductive loads, featuring a 350 V collector-emitter sustaining voltage (BV_CEO(sus)), 8 A DC collector current rating, and 80 W collector dissipation at T_C = 25°C - used in motor control, relay drivers, and ignition systems.

For engineers reviewing the KSE5741TU datasheet, pinout, applications, or equivalent options, this device offers verified high-voltage switching capability with documented saturation behavior (V_CE(sat) = 2–3 V at 4–8 A), fast turn-off timing (t_F = 2 µs), and TO-220 package thermal performance up to 150°C junction temperature.

Technical Context

The KSE5741TU integrates two cascaded NPN transistors in a monolithic Darlington configuration to achieve high DC current gain (h_FE = 50–400) and low base drive requirements, enabling efficient switching of inductive loads without external amplification. Its rugged construction supports repetitive avalanche energy handling and reverse-bias safe operating area (RBSOA) compliance up to 250 V.

Designed for hard-switching applications, it delivers defined timing characteristics: t_D = 0.04 µs, t_R = 0.5 µs, t_S = 8 µs, and t_F = 2 µs under V_CC = 250 V, I_C(pk) = 6 A, and matched base drive conditions - critical for snubberless inverter and solenoid driver designs.

Key Specifications

Parameter	Value and Actual Design Meaning
BV_CEO(sus)	350 V - Sustains 350 V between collector and emitter at I_C = 50 mA, IB = 0; defines maximum inductive flyback voltage tolerance
I_C (DC)	8 A - Continuous collector current capability at T_C = 25°C; sets steady-state load driving capacity
V_CE(sat)	2–3 V - Saturation voltage range at I_C = 4–8 A and I_B = 0.2–0.4 A; determines conduction loss and thermal load
h_FE	50–400 - DC current gain across I_C = 0.5–4 A; enables low-base-current control of high-power loads
t_F	2 µs - Fall time under V_CC = 250 V, I_C(pk) = 6 A; limits switching losses during turn-off transitions
P_C	80 W - Maximum collector power dissipation at T_C = 25°C; defines heatsink sizing baseline for continuous operation
T_J	150 °C - Maximum allowable junction temperature; constrains thermal design margin in enclosed environments

Pinout & Package

Package: TO-220 (3-lead, straight lead, insulated tab). Dimensions per Fairchild Rev. A1: 15.90 mm × 10.08 mm × 18.95 mm max, with mounting hole ø3.60 mm.

Pin/Terminal	Circuit Role	Design Meaning
1 (Base)	Control input terminal	Receives base current to initiate and sustain Darlington conduction; requires ≥0.2 A for full 8 A output
2 (Collector)	High-side power path	Connected to inductive load or supply rail; carries full load current and withstands 350 V sustaining voltage
3 (Emitter)	Low-side return path	Common emitter node tied to ground or low-side switch; referenced for base drive and current sensing

Key Features

Feature	Design Value
High-voltage sustaining capability	350 V BV_CEO(sus) enables direct replacement of lower-voltage switches in 24–48 V industrial systems with inductive kickback
Low-saturation voltage	V_CE(sat) ≤ 3 V at 8 A reduces conduction loss to < 24 W, easing thermal management vs. standard bipolar transistors
Fast switching performance	Combined t_R + t_F = 2.5 µs supports PWM frequencies up to ~100 kHz in regulated power stages
Rugged SOA profile	Reverse-bias safe operating area validated to 250 V/6 A ensures reliability in snubberless relay and solenoid drive circuits
TO-220 mechanical compatibility	Standard footprint and mounting hole allow drop-in integration into existing PCB layouts designed for similar power transistors

Applications

Small Engine Ignition	DC Motor Control
Use Scenario: Triggering spark plug discharge in 12 V gasoline engine ignition coils via primary winding switching. IC Role / Device Role / Timing Role: High-voltage Darlington switch controlling coil primary current; handles 350 V flyback and 8 A peak pulse current. Use Value: Eliminates need for external snubbers due to RBSOA compliance and 8 µs storage time tolerance under rated conditions.	Use Scenario: H-bridge or single-ended drive of brushed DC motors in industrial actuators (e.g., valve positioners, conveyor modules). IC Role / Device Role / Timing Role: Power stage switch delivering 8 A continuous current with <3 V saturation drop to minimize I²R heating. Use Value: Enables compact heatsink design with 80 W dissipation margin at 25°C case temperature, supporting duty cycles up to 100%.
Switching Regulator	Relay/Solenoid Driver
Use Scenario: Main switching element in 48 V offline flyback or forward converter secondary-side synchronous rectification or primary-side switching. IC Role / Device Role / Timing Role: High-voltage power switch operating at ≤100 kHz with t_F = 2 µs and t_S = 8 µs to limit switching loss. Use Value: Reduces gate drive complexity versus MOSFETs while maintaining efficiency in medium-frequency SMPS designs.	Use Scenario: Driving 24–48 V DC relays and solenoids in PLC I/O modules and HVAC control panels. IC Role / Device Role / Timing Role: Inductive load switch with built-in base-emitter clamp diode (VF = 2.5 V) to suppress back-EMF. Use Value: Prevents external flyback diode requirement, simplifying BOM and board layout for high-reliability industrial control.

Small Engine Ignition

DC Motor Control

Use Scenario: Triggering spark plug discharge in 12 V gasoline engine ignition coils via primary winding switching.

IC Role / Device Role / Timing Role: High-voltage Darlington switch controlling coil primary current; handles 350 V flyback and 8 A peak pulse current.

Use Value: Eliminates need for external snubbers due to RBSOA compliance and 8 µs storage time tolerance under rated conditions.

Use Scenario: H-bridge or single-ended drive of brushed DC motors in industrial actuators (e.g., valve positioners, conveyor modules).

IC Role / Device Role / Timing Role: Power stage switch delivering 8 A continuous current with <3 V saturation drop to minimize I²R heating.

Use Value: Enables compact heatsink design with 80 W dissipation margin at 25°C case temperature, supporting duty cycles up to 100%.

Switching Regulator

Relay/Solenoid Driver

Use Scenario: Main switching element in 48 V offline flyback or forward converter secondary-side synchronous rectification or primary-side switching.

IC Role / Device Role / Timing Role: High-voltage power switch operating at ≤100 kHz with t_F = 2 µs and t_S = 8 µs to limit switching loss.

Use Value: Reduces gate drive complexity versus MOSFETs while maintaining efficiency in medium-frequency SMPS designs.

Use Scenario: Driving 24–48 V DC relays and solenoids in PLC I/O modules and HVAC control panels.

IC Role / Device Role / Timing Role: Inductive load switch with built-in base-emitter clamp diode (VF = 2.5 V) to suppress back-EMF.

Use Value: Prevents external flyback diode requirement, simplifying BOM and board layout for high-reliability industrial control.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD127G	PNP complement; 80 V V_CEO, 8 A I_C, TO-263 package; lacks 350 V sustaining rating and RBSOA validation	Only suitable for low-voltage (<100 V) switching; cannot replace KSE5741TU in ignition or 48 V inverter designs	Select only when polarity inversion and lower voltage operation are required; not a functional substitute
BU508AF	NPN; 1500 V V_CEO, 8 A I_C, slower t_F = 10 µs, TO-3PF package; no Darlington gain advantage	Used in CRT flyback and high-voltage AC line switching; higher voltage margin but poorer switching efficiency	Choose for ultra-high-voltage isolation needs where gain and speed are secondary to breakdown rating

Compared with MJD127G and BU508AF, the KSE5741TU uniquely balances 350 V sustaining voltage, Darlington-level current gain (h_FE ≥ 200 at 4 A), and sub-3 µs total switching time - making it optimal for cost-sensitive, thermally constrained 24–48 V inductive switching where both voltage headroom and drive simplicity matter.

Availability

KSE5741TU is available at Aetrix Electronics and suitable for small engine ignition, DC motor control, and relay/solenoid driver applications requiring stable component supply, long-lifecycle support, and traceable sourcing from original manufacturer channels.

Supply support for KSE5741TU 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power discrete devices, analog ICs, and interface solutions before its acquisition by ON Semiconductor in 2016.

The KSE5741TU belongs to Fairchild's high-voltage power Darlington transistor family, engineered specifically for robust, snubberless switching in automotive ignition, industrial actuation, and power conversion systems.

FAQ

What is the maximum collector-emitter sustaining voltage for KSE5741TU?

The KSE5741TU has a guaranteed minimum collector-emitter sustaining voltage (BV_CEO(sus)) of 350 V at I_C = 50 mA and I_B = 0, as specified in the Fairchild Rev. A1 datasheet. This rating reflects its ability to block transient inductive voltages without breakdown, distinguishing it from the 300 V KSE5740 and 400 V KSE5742 variants.

Does KSE5741TU include an integrated base-emitter clamp diode?

No, the KSE5741TU does not integrate a base-emitter clamp diode. However, its datasheet specifies V_EBO = 8 V and includes a separate diode forward voltage (V_F = 2.5 V at I_F = 5 A) parameter - indicating an internal emitter-base junction that can conduct in reverse bias, but not as a dedicated clamping structure. External protection remains recommended for high-dV/dt environments.

What is the thermal resistance from junction to case for KSE5741TU?

The KSE5741TU datasheet does not explicitly list R_θJC. However, based on its 80 W power dissipation rating at T_C = 25°C and 150°C maximum junction temperature, the implied R_θJC is approximately 1.56°C/W - calculated as (T_J(max) − T_C) / P_C = (150 − 25) / 80. This value aligns with typical TO-220 packaged Darlington transistors.

Can KSE5741TU be used in parallel configurations for higher current handling?

Parallel operation of KSE5741TU devices is not recommended without individual emitter resistors and matched h_FE sorting. The datasheet shows h_FE variation from 50 to 400 across operating points, and V_BE(sat) increases with current - leading to thermal runaway risk if unbalanced. For >8 A applications, consider higher-rated alternatives or forced-air-cooled single-device implementation.

Is KSE5741TU RoHS compliant?

The original KSE5741TU datasheet (Rev. A1, June 2001) predates RoHS legislation and does not declare compliance. Post-acquisition, ON Semiconductor maintains legacy Fairchild part status under "legacy product" classification. Current production lots supplied by Aetrix Electronics meet RoHS 2011/65/EU requirements, with lead-free finish and halogen-free molding compound confirmed per material declarations.

KSE5741TU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN - Darlington

Current - Collector (Ic) (Max):: 8 A

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

Vce Saturation (Max) @ Ib, Ic:: 3V @ 400mA, 8A

Current - Collector Cutoff (Max):: -

DC Current Gain (hFE) (Min) @ Ic, Vce:: 200 @ 4A, 5V

Power - Max:: 80 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220-3

KSE5741TU FAQ

1.How can I place an order for KSE5741TU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSE5741TU 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 KSE5741TU reliable?

The price and inventory of KSE5741TU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSE5741TU is usually 5 days.

3.What payment methods are accepted for KSE5741TU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSE5741TU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSE5741TU?

KSE5741TU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSE5741TU 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 KSE5741TU?

For technical support, including KSE5741TU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSE5741TU requirements.

6.How does Aetrix verify that KSE5741TU is sourced from the original manufacturer or authorized distributors?

All KSE5741TU 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 KSE5741TU meets industry standards.

7.What is the process for return or replacement of KSE5741TU?

All KSE5741TU units undergo pre-shipment inspection (PSI). If there is an issue with KSE5741TU, 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 KSE5741TU part is unused and in its original packaging.

Return procedure for KSE5741TU:

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…