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 > FETs, MOSFETs > FETs, MOSFETs

STMicroelectronics STU3N45K3

Name: STU3N45K3
Brand: STMicroelectronics
SKU: STU3N45K3
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: STU3N45K3

Manufacturer:: STMicroelectronics

Category:: FETs, MOSFETs

Package:: TO-251-3 Short Leads, IPAK, TO-251AA

Datasheet:: STU3N45K3.pdf

Description:: MOSFET N-CH 450V 1.8A IPAK

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:9,994

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

Product details

Overview

STU3N45K3 from STMicroelectronics is an N-channel 450 V, 3.3 Ω typ. (4 Ω max.), 1.8 A MDmesh K3 Power MOSFET in IPAK (TO-251) package, featuring 100% avalanche tested operation, 12 V/ns dv/dt capability, and Zener-protected gate. It serves as a high-reliability switching device in offline SMPS primary-side circuits.

For engineers reviewing the STU3N45K3 datasheet, STU3N45K3 pinout, STU3N45K3 application, or STU3N45K3 equivalent, key selection criteria include R_DS(on) stability over temperature, low C_oss(er) (18 pF), fast trr (175 ns), EAS rating (60 mJ), and IPAK thermal resistance (R_thJC = 4.63 °C/W).

Technical Context

This MDmesh K3 MOSFET employs an optimized vertical structure to reduce on-resistance while maintaining high voltage blocking and robust dynamic performance. Its low intrinsic capacitance (C_iss = 164 pF, C_oss = 17 pF) and improved diode reverse recovery (Q_rr = 550 nC, trr = 175 ns) enable high-frequency hard-switching operation up to 225 V bus conditions.

The device integrates Zener protection between gate and source, supports ±30 V V_GS, and delivers stable V_GS(th) (3–4.5 V) across –55 to 150 °C. Avalanche ruggedness is validated at I_AR = 0.9 A and E_AS = 60 mJ under defined unclamped inductive load conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	450 V - Sustains full mains-derived DC bus voltages in universal-input offline converters without derating.
R_DS(on) max	4 Ω @ V_GS = 10 V, I_D = 0.6 A - Enables low conduction loss in <2 W output flyback and PSR designs.
I_D cont @ T_C = 25 °C	1.8 A - Supports continuous operation in compact, thermally constrained IPAK-mounted topologies.
E_AS	60 mJ @ V_DD = 50 V, I_AR = 0.9 A - Provides margin for transient overloads and startup surges in unclamped inductive switching.
C_oss(er)	18 pF - Reduces turn-off energy loss and improves efficiency in high-frequency quasi-resonant converters.
trr	175 ns @ I_SD = 1.8 A, di/dt = 100 A/µs - Minimizes commutation loss and EMI generation during diode recovery.
dv/dt capability	12 V/ns - Ensures noise immunity and prevents spurious turn-on in high-dV/dt environments like PFC stages.

Pinout & Package

IPAK (TO-251) type C package: surface-mount, single-ended leadframe with exposed drain tab for thermal enhancement. Tab is electrically connected to drain (D). Standard ECOPACK-compliant construction.

Pin/Terminal	Circuit Role	Design Meaning
1 (G)	Gate	Control terminal; accepts 10 V drive for full enhancement; Zener-protected against ±30 V transients.
2 (TAB/D)	Drain (exposed tab)	Main high-side power path; electrically tied to drain; provides low-thermal-resistance path to heatsink.
3 (S)	Source	Power return and reference node; used for current sensing and gate drive referencing in low-side configurations.

Key Features

Feature	Design Value
100% avalanche tested	Guarantees ruggedness under unclamped inductive switching stress without screening failure.
Extremely high dv/dt capability	12 V/ns rating prevents false triggering in noisy high-voltage switching nodes.
Very low intrinsic capacitance	C_iss = 164 pF, C_oss = 17 pF - reduces switching losses and enables >100 kHz operation.
Improved diode reverse recovery	Q_rr = 550 nC, trr = 175 ns - lowers recovery loss and EMI vs legacy MDmesh K2 devices.
Zener-protected gate	Integrated gate-source Zener clamps transients to ±20 V, eliminating need for external protection.

Applications

AC-DC Adapter Primary Switch

LED Driver Flyback Controller

Use Scenario: Universal-input (90–264 V_AC) 12 W flyback converter powering USB-C PD adapters.

IC Role / Device Role / Timing Role: Primary-side high-voltage switching element operating in discontinuous conduction mode (DCM) at 65–100 kHz.

Use Value: Low R_DS(on) and C_oss(er) reduce conduction and turn-off losses, enabling >88% efficiency at full load without active cooling.

Use Scenario: Isolated constant-current LED driver for commercial downlights (24 V_OUT/350 mA).

IC Role / Device Role / Timing Role: Primary-side switch in quasi-resonant flyback topology with valley-switching control.

Use Value: Fast trr and low Q_rr minimize diode recovery noise, easing EMI filter design and meeting CISPR-15 Class B limits.

Industrial SMPS Auxiliary Supply

Smart Meter Power Stage

Use Scenario: 5 V/1 A auxiliary supply derived from 400 V DC bus in PLC power modules.

IC Role / Device Role / Timing Role: Low-duty-cycle, high-V_DS switch in self-oscillating flyback configuration.

Use Value: 450 V rating and 100% avalanche testing ensure reliability during line surges and brownouts per IEC 61000-4-5.

Use Scenario: Mains-connected polyphase smart meter with integrated isolation and metrology.

IC Role / Device Role / Timing Role: Primary-side switch in ultra-low-power auxiliary supply powering real-time clock and communication ICs.

Use Value: Zener-protected gate and low IDSS (<1 µA) prevent leakage-induced timing drift and maintain accuracy over 15-year service life.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage MOSFET switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
STP3N45K3	TO-220 package, identical electrical specs (450 V, 4 Ω, 1.8 A), higher R_thJC (3.5 °C/W vs 4.63 °C/W), no exposed tab.	Requires larger heatsink area; unsuitable for space-constrained PCB layouts where IPAK footprint is critical.	Select when board-level thermal mass allows TO-220 mounting and cost-per-watt optimization is prioritized.
STU2N45K3	Same IPAK package but lower I_D (1.3 A), higher R_DS(on) (5.5 Ω max), reduced E_AS (35 mJ).	Limited to sub-10 W designs; insufficient avalanche margin for industrial surge immunity requirements.	Choose only for cost-sensitive, low-power consumer adapters where full 1.8 A capability is unused.

Compared with STP3N45K3 and STU2N45K3, STU3N45K3 uniquely balances IPAK's compact footprint with 1.8 A current handling and 60 mJ avalanche energy-enabling reliable, space-efficient 12–15 W offline supplies without thermal compromise.

Availability

STU3N45K3 is available at Aetrix Electronics and suitable for AC-DC adapters, LED drivers, industrial auxiliary supplies, and smart meter power stages requiring stable component supply and long-term manufacturability.

Supply support for STU3N45K3 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 microcontrollers, power devices, sensors, and analog ICs for industrial, automotive, and consumer markets.

The MDmesh K3 product line targets high-efficiency, high-reliability power conversion in offline SMPS, delivering optimized R_DS(on)-to-capacitance trade-offs for 380–500 V DC bus applications.

FAQ

What is the maximum continuous drain current at 100 °C case temperature?

The STU3N45K3 supports 1.8 A continuous drain current at T_C = 25 °C, derating linearly to approximately 1.1 A at T_C = 100 °C based on its safe operating area curve and R_thJC = 4.63 °C/W. This derating ensures junction temperature remains below 150 °C under steady-state conduction.

Does STU3N45K3 require external gate protection?

No. The device integrates a Zener diode between gate and source, clamping transient gate-source voltage to ±20 V. External gate resistors (e.g., 4.7 Ω) are still required for controlled switching speed and ringing suppression, but discrete TVS or Zener components are unnecessary.

How does the diode reverse recovery performance compare to standard silicon MOSFETs?

STU3N45K3 achieves trr = 175 ns and Q_rr = 550 nC at I_SD = 1.8 A, di/dt = 100 A/µs - ~40% lower Q_rr than comparable 450 V planar MOSFETs. This results in measurable reduction of peak-to-peak switching node ringing and common-mode EMI in flyback converters.

Can STU3N45K3 be used in synchronous rectification topologies?

No. As a single N-channel high-voltage MOSFET with source-drain diode optimized for recovery (not conduction), it lacks the low forward voltage and bidirectional conduction capability required for SR. Its body diode is intended for freewheeling, not primary rectification; dedicated SR controllers and logic-level FETs are needed instead.

STU3N45K3 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: SuperMESH3™

Package/Case:: TO-251-3 Short Leads, IPAK, TO-251AA

Packaging:: Tube

Product Status:: Active

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 450 V

Current - Continuous Drain (Id) @ 25°C:: 1.8A (Tc)

Drive Voltage (Max Rds On, Min Rds On):: 10V

Rds On (Max) @ Id, Vgs:: 3.8Ohm @ 500mA, 10V

Vgs(th) (Max) @ Id:: 4.5V @ 50µA

Gate Charge (Qg) (Max) @ Vgs:: 6 nC @ 10 V

Vgs (Max):: ±30V

Input Capacitance (Ciss) (Max) @ Vds:: 150 pF @ 25 V

FET Feature:: -

Power Dissipation (Max):: 27W (Tc)

Operating Temperature:: -

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-251 (IPAK)

STU3N45K3 FAQ

1.How can I place an order for STU3N45K3 through Aetrix?

Please submit a Request for Quotation (RFQ) for STU3N45K3 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 STU3N45K3 reliable?

The price and inventory of STU3N45K3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STU3N45K3 is usually 5 days.

3.What payment methods are accepted for STU3N45K3?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STU3N45K3 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STU3N45K3?

STU3N45K3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STU3N45K3 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 STU3N45K3?

For technical support, including STU3N45K3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STU3N45K3 requirements.

6.How does Aetrix verify that STU3N45K3 is sourced from the original manufacturer or authorized distributors?

All STU3N45K3 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 STU3N45K3 meets industry standards.

7.What is the process for return or replacement of STU3N45K3?

All STU3N45K3 units undergo pre-shipment inspection (PSI). If there is an issue with STU3N45K3, 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 STU3N45K3 part is unused and in its original packaging.

Return procedure for STU3N45K3:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-10 Schmitt Trigger Explained: Hysteresis, Circuits, Inverters and Applications

Schmitt triggers use separate rising and falling thresholds to stabilize slow or noisy signals. This guide covers hysteresis, 74HC14 and 74HCT14 selection, comparator calculations, RC oscillators and p…

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…