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Home > Products > Discrete Semiconductor Products > Transistors > FETs, MOSFETs > FETs, MOSFETs

STMicroelectronics STFI20NK50Z

Name: STFI20NK50Z
Brand: STMicroelectronics
SKU: STFI20NK50Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STFI20NK50Z

Manufacturer:: STMicroelectronics

Category:: FETs, MOSFETs

Package:: TO-262-3 Full Pack, I2PAK

Datasheet:: STFI20NK50Z.pdf

Description:: MOSFET N-CH 500V 17A I2PAKFP

Quantity:: RFQ Add To RFQ list

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Inventory:760

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Product details

Overview

STFI20NK50Z from STMicroelectronics is an N-channel 500 V, 0.23 Ω (typ), 17 A Zener-protected SuperMESH™ Power MOSFET in I²PAKFP (TO-281) package. It delivers high dv/dt immunity (4.5 V/ns), 100% avalanche tested ruggedness, and integrated gate-source Zener protection (30 V breakdown). Used in offline SMPS, AC-DC adapters, and industrial motor control where fast switching and transient robustness are critical.

For engineers reviewing the STFI20NK50Z datasheet, STFI20NK50Z pinout, STFI20NK50Z application, or STFI20NK50Z equivalent, key selection factors include its 40 W total dissipation at TC = 25 °C, 3.1 °C/W junction-to-case thermal resistance, 850 mJ single-pulse avalanche energy, and built-in back-to-back Zener diodes eliminating external gate protection components.

Technical Context

This MOSFET employs ST's SuperMESH™ strip-based layout to minimize R_DS(on) while preserving high voltage capability and switching speed. Its internal structure integrates dual Zener diodes between gate and source for ESD (6 kV HBM) and transient overvoltage clamping without external parts.

The device operates with ±30 V gate drive, supports 500 V drain-source blocking, and maintains stable threshold voltage (3–4.5 V) across temperature. Its low C_iss (2600 pF) and optimized Q_g (85 nC) enable efficient hard-switching up to several hundred kHz in flyback and resonant topologies.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DSS	500 V - Supports primary-side switching in universal-input 85–265 VAC offline converters without derating.
R_DS(on) max	0.27 Ω - Enables <1.5 W conduction loss at 17 A DC, suitable for medium-power (<150 W) SMPS designs.
I_D (T_C = 25 °C)	17 A - Continuous current rating under heatsink-cooled conditions; derates to 10.71 A at 100 °C case temperature.
E_AS	850 mJ - Single-pulse unclamped inductive switching energy tolerance ensures reliability during startup or fault events.
dv/dt	4.5 V/ns - High immunity to parasitic turn-on in noisy high-voltage environments such as PFC stages.
V_ISO	2500 V RMS - Insulation withstand voltage from all three leads to heatsink enables safe mounting on live metal chassis.
Q_g	85 nC - Total gate charge value determines driver strength requirement; compatible with standard 1-A peak gate drivers.

Pinout & Package

The STFI20NK50Z is housed in an insulated I²PAKFP (TO-281) package with creepage-enhanced leadframe and integral heatsink plate. The package provides full electrical isolation between leads and heatsink surface.

Pin/Terminal	Circuit Role	Design Meaning
G (Pin 1)	Gate terminal	Control input; accepts ±30 V drive; protected by integrated 30 V Zener diode to clamp transients.
D (Pin 2)	Drain terminal	High-voltage power node; connected to heatsink plate via isolated mounting; rated for 500 V blocking.
S (Pin 3)	Source terminal	Power return path; forms common reference for gate drive; carries full load current (17 A continuous).

Key Features

Feature	Design Value
Fully insulated package	I²PAKFP provides 2500 V RMS isolation between pins and heatsink, enabling direct mounting on grounded chassis without insulating pads.
Zener-protected gate	Integrated back-to-back Zeners clamp V_GS to ±30 V, eliminating need for external TVS or resistor-Zener networks.
100% avalanche tested	Every unit undergoes unclamped inductive switching test at rated current, guaranteeing ruggedness in real-world fault conditions.
SuperMESH™ technology	Optimized strip layout achieves 0.23 Ω R_DS(on) at 500 V, reducing conduction losses vs. conventional planar MOSFETs of same voltage class.

Applications

AC-DC Adapter Primary Switch

Industrial Motor Starter

Use Scenario: 65–120 W universal-input offline flyback converter powering consumer electronics.

IC Role / Device Role / Timing Role: Main power switch controlling energy transfer from primary winding; operates in discontinuous conduction mode at ~65 kHz.

Use Value: Low R_DS(on) minimizes conduction loss; high dv/dt immunity prevents false triggering from transformer leakage spikes.

Use Scenario: Solid-state relay driving 3-phase induction motor starter coils in HVAC control panels.

IC Role / Device Role / Timing Role: High-voltage interface switch isolating 240 VAC control logic from coil supply; driven by microcontroller GPIO.

Use Value: 2500 V isolation allows direct PCB mounting on metal enclosure; Zener protection sustains repeated coil-dead-time voltage reversals.

LED Streetlight Driver

UPS Inverter Stage

Use Scenario: Two-switch forward converter supplying constant current to 100–150 W LED arrays in outdoor lighting.

IC Role / Device Role / Timing Role: Primary-side synchronous rectifier replacement; handles 500 V bus with 17 A peak current pulses.

Use Value: Avalanche-rated operation absorbs inductive kickback from output choke; 850 mJ E_AS ensures survival during grid-surge events.

Use Scenario: Half-bridge leg in 1 kVA online UPS inverter converting 380 VDC bus to 230 VAC output.

IC Role / Device Role / Timing Role: High-side switching element operating with bootstrap gate drive; switched at 20 kHz PWM frequency.

Use Value: Low Q_g (85 nC) reduces gate drive power; low C_oss (328 pF) limits capacitive turn-off loss during zero-voltage switching transitions.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
STP20NK50Z	Same die, TO-220FP package; no insulation between leads and heatsink plate; R_thj-case = 3.0 °C/W (slightly better thermal performance).	Requires insulating washer when mounted on conductive chassis; unsuitable for direct-chassis mounting.	Select when thermal priority outweighs isolation needs and chassis grounding permits external insulation.
FQP20N50	500 V, 0.27 Ω, 20 A; no integrated Zener protection; lower E_AS (520 mJ); higher Q_g (105 nC).	Lacks gate transient protection; requires external Zener + series resistor; less rugged in unclamped inductive switching.	Select only if cost sensitivity dominates and external protection circuitry is acceptable.

Compared with STP20NK50Z and FQP20N50, the STFI20NK50Z uniquely combines certified 2500 V isolation, integrated gate Zener clamping, and 100% avalanche testing-making it the only choice for safety-critical, chassis-mounted, high-reliability offline power stages.

Availability

STFI20NK50Z is available at Aetrix Electronics and suitable for AC-DC adapters, industrial motor starters, LED streetlight drivers, and UPS inverter stages requiring stable component supply and long-term manufacturing continuity.

Supply support for STFI20NK50Z 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, designing and manufacturing analog, digital, and mixed-signal ICs, discrete devices, and MEMS sensors for automotive, industrial, and consumer markets.

The SuperMESH™ Power MOSFET product line targets high-efficiency, high-reliability offline power conversion-emphasizing ruggedness, low conduction loss, and integration of protection features for simplified system design.

FAQ

What is the maximum safe operating temperature for STFI20NK50Z?

The absolute maximum junction temperature is 150 °C. Operation above this risks permanent degradation of the silicon die and Zener protection structure. Thermal design must ensure T_j ≤ 150 °C under worst-case ambient and load conditions, using the specified R_thj-case = 3.1 °C/W and heatsink thermal resistance.

Can STFI20NK50Z replace STP20NK50Z without board modifications?

No. Although electrically identical, STFI20NK50Z uses the I²PAKFP (TO-281) package with insulated leads, while STP20NK50Z uses TO-220FP with non-insulated leads. Mounting hole pattern, lead pitch, and isolation requirements differ-requiring PCB layout revision and mechanical requalification.

Does the built-in Zener protect against both positive and negative gate transients?

Yes. The device integrates back-to-back Zener diodes between gate and source, providing symmetrical ±30 V clamping (V_(BR)GSO = 30 V). This protects against both positive overvoltage (e.g., ESD, ringing) and negative undershoot (e.g., Miller-induced negative spikes during high di/dt switching).

Is STFI20NK50Z suitable for use in automotive applications?

No. STFI20NK50Z is not qualified to AEC-Q101 and lacks automotive-grade screening, temperature range extension (−40 to 150 °C), or PPAP documentation. ST explicitly states non-automotive grade parts are used in automotive applications at the user's own risk and without warranty.

STFI20NK50Z Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: SuperMESH™

Package/Case:: TO-262-3 Full Pack, I2PAK

Packaging:: Tube

Product Status:: Obsolete

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 500 V

Current - Continuous Drain (Id) @ 25°C:: 17A (Tc)

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

Rds On (Max) @ Id, Vgs:: 270mOhm @ 8.5A, 10V

Vgs(th) (Max) @ Id:: 4.5V @ 100µA

Gate Charge (Qg) (Max) @ Vgs:: 119 nC @ 10 V

Vgs (Max):: ±30V

Input Capacitance (Ciss) (Max) @ Vds:: 2600 pF @ 25 V

FET Feature:: -

Power Dissipation (Max):: 40W (Tc)

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-281 (I2PAKFP)

STFI20NK50Z FAQ

1.How can I place an order for STFI20NK50Z through Aetrix?

Please submit a Request for Quotation (RFQ) for STFI20NK50Z 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 STFI20NK50Z reliable?

The price and inventory of STFI20NK50Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STFI20NK50Z is usually 5 days.

3.What payment methods are accepted for STFI20NK50Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STFI20NK50Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STFI20NK50Z?

STFI20NK50Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STFI20NK50Z 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 STFI20NK50Z?

For technical support, including STFI20NK50Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STFI20NK50Z requirements.

6.How does Aetrix verify that STFI20NK50Z is sourced from the original manufacturer or authorized distributors?

All STFI20NK50Z 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 STFI20NK50Z meets industry standards.

7.What is the process for return or replacement of STFI20NK50Z?

All STFI20NK50Z units undergo pre-shipment inspection (PSI). If there is an issue with STFI20NK50Z, 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 STFI20NK50Z part is unused and in its original packaging.

Return procedure for STFI20NK50Z:

1.Submit a request within 90 days.

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

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