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

STMicroelectronics STF12N120K5

Name: STF12N120K5
Brand: STMicroelectronics
SKU: STF12N120K5
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STF12N120K5

Manufacturer:: STMicroelectronics

Category:: FETs, MOSFETs

Package:: TO-220-3 Full Pack

Datasheet:: STF12N120K5.pdf

Description:: MOSFET N-CH 1200V 12A TO220FP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

STF12N120K5 from STMicroelectronics is a high-voltage N-channel Power MOSFET based on MDmesh K5 technology, designed for primary-side switching in offline SMPS, PFC stages, and industrial HV DC-DC converters. It delivers 1200 V V_DS, 690 mΩ R_DS(on) max at 10 V V_GS, 12 A continuous drain current (T_C = 25 °C), and is housed in a TO-220FP package with insulated tab.

For engineers reviewing the STF12N120K5 datasheet, STF12N120K5 pinout, STF12N120K5 application, or STF12N120K5 equivalent, key selection criteria include avalanche ruggedness (215 mJ E_AS), ultra-low Q_g (44.2 nC), dv/dt immunity (50 V/ns), and Zener-protected gate - critical for reliable operation in hard-switched 1 kV+ topologies.

Technical Context

This device employs ST's proprietary vertical MDmesh K5 structure to achieve a low figure of merit (R_DS(on) × Q_g = 30.5 Ω·nC), enabling high power density in space-constrained HV applications. Its 100% avalanche-tested construction ensures robustness under unclamped inductive switching stress.

The integrated body diode features fast recovery (t_rr = 630 ns @ T_J = 25 °C) and low Q_rr (12.6 μC), reducing switching losses in quasi-resonant and LLC converters. The TO-220FP package provides 2.5 kV RMS insulation between leads and heat sink, supporting reinforced isolation requirements.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	1200 V - supports direct rectified mains input up to 850 V_AC with margin for surge and ringing.
R_DS(on) max	690 mΩ @ V_GS = 10 V, T_C = 25 °C - enables <1.5 W conduction loss at 12 A, critical for >95% efficiency designs.
Q_g	44.2 nC - reduces gate drive power and allows use of smaller, lower-cost drivers in high-frequency (>100 kHz) operation.
E_AS	215 mJ @ T_J = 25 °C - guarantees single-pulse avalanche survivability without derating in flyback or forward converter overloads.
dv/dt ruggedness	50 V/ns - prevents false turn-on during high-slew-rate voltage transients in bridge-leg or phase-shifted topologies.
R_thJC	3.1 °C/W - enables 40 W dissipation at ΔT = 124 °C, supporting compact heatsink designs in enclosed industrial enclosures.

Pinout & Package

STF12N120K5 uses the TO-220FP (Type B) package with insulated tab, providing creepage/clearance compliance for reinforced isolation. The plastic body isolates the drain (tab) from mounting surface, eliminating need for insulating washers in PCB-mounted heatsinks.

Pin/Terminal	Circuit Role	Design Meaning
Tab (Drain)	High-side switch node / Heat sink interface	Electrically isolated metal tab serves as both drain terminal and thermal path; rated for 2.5 kV RMS insulation to heatsink.
Lead 1 (Gate)	Control input	Zener-protected gate accepts ±30 V V_GS; low 3.5 Ω intrinsic R_g minimizes gate oscillation risk.
Lead 3 (Source)	Reference return / Current sense node	Low-inductance source connection enables accurate current-mode control and minimizes common-source inductance in high-dI/dt switching.

Key Features

Feature	Design Value
MDmesh K5 vertical structure	Reduces R_DS(on) × Q_g by 40% vs prior K3 generation, enabling higher frequency operation without efficiency penalty.
100% unclamped inductive avalanche tested	Guarantees minimum 215 mJ single-pulse energy handling - eliminates need for external snubbers in cost-sensitive flyback designs.
Zener-protected gate	Integrated 20 V gate clamp prevents oxide damage during ESD events or gate driver faults, improving field reliability.
Ultra-low C_oss (110 pF) & C_rss (0.6 pF)	Minimizes capacitive turn-off losses and improves light-load efficiency in resonant converters operating above 200 kHz.

Applications

Industrial AC-DC Power Supplies

Photovoltaic String Inverters

Use Scenario: Primary-side switch in 1–3 kW offline flyback or forward converters powering PLCs and motor drives.

IC Role / Device Role / Timing Role: High-voltage switching element handling full rectified line voltage with tight duty-cycle control.

Use Value: 1200 V rating and 50 V/ns dv/dt immunity prevent spurious turn-on during line surges, reducing system-level protection component count.

Use Scenario: DC-DC boost stage in string inverters stepping up PV array output (600–1000 V) to inverter bus.

IC Role / Device Role / Timing Role: Unidirectional high-efficiency power switch in hard-switched or quasi-resonant topology.

Use Value: Low 620 mΩ typ. R_DS(on) cuts conduction loss by >1.2 W vs legacy 1200 V MOSFETs, directly improving inverter efficiency at partial load.

EV On-Board Chargers (OBC)

High-Voltage Industrial SMPS

Use Scenario: Isolated DC-DC stage converting 400 V battery to 12/48 V auxiliary rails in bidirectional OBC systems.

IC Role / Device Role / Timing Role: Primary-side switch in phase-shifted full-bridge or dual-active-bridge topology.

Use Value: Fast 630 ns t_rr and low 12.6 μC Q_rr reduce body-diode conduction loss during zero-voltage switching transitions, lowering thermal stress.

Use Scenario: Main switch in 5–10 kW industrial welders, plasma cutters, or laser drivers requiring >1 kV blocking.

IC Role / Device Role / Timing Role: Robust main power switch subjected to repetitive avalanche and high di/dt stress.

Use Value: 100% avalanche testing and 48 A pulsed ID ensure reliable operation under short-circuit and arc-fault conditions without derating.

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
STFW12N120K5	Same die, TO-3PF package with higher R_thJC (1.98 °C/W) and 3.5 kV isolation rating.	Better thermal performance in forced-air or liquid-cooled systems; larger footprint limits PCB density.	Select when thermal budget is tighter than board area constraints, especially in open-frame industrial supplies.
IXTH12N120	1200 V, 750 mΩ R_DS(on), 40 nC Q_g, no integrated Zener protection, TO-247 package.	Lacks gate Zener and avalanche certification; requires external gate clamping and careful SOA management.	Choose only if gate drive circuit includes discrete Zener clamping and design has margin for reduced ruggedness.

Compared with STFW12N120K5, STF12N120K5 trades 1.12 °C/W higher junction-to-case thermal resistance for 30% smaller footprint and simplified mounting; versus IXTH12N120, it adds certified avalanche robustness and gate protection at modest R_DS(on) penalty.

Availability

STF12N120K5 is available at Aetrix Electronics and suitable for industrial AC-DC power supplies, photovoltaic string inverters, and EV on-board chargers requiring stable component supply across multi-year production cycles.

Supply support for STF12N120K5 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, specializing in power management, microcontrollers, and analog/mixed-signal ICs for industrial, automotive, and consumer markets.

This device belongs to ST's MDmesh K5 high-voltage Power MOSFET family, engineered specifically for high-efficiency, high-power-density offline switching applications where R_DS(on), Q_g, and ruggedness must be simultaneously optimized.

FAQ

Is STF12N120K5 suitable for zero-voltage switching (ZVS) topologies?

Yes - its ultra-low C_oss (110 pF) and C_rss (0.6 pF), combined with fast body diode recovery (t_rr = 630 ns), enable reliable ZVS operation in LLC and phase-shifted full-bridge converters up to 300 kHz. The low Q_g further reduces gate drive losses during high-frequency soft-switching transitions.

What is the maximum recommended gate resistor value for reliable switching?

For standard 10 V gate drive, R_G ≤ 10 Ω is recommended to ensure turn-on time <35 ns and suppress parasitic oscillation, given the device's 3.5 Ω intrinsic gate resistance and 44.2 nC total charge. Higher values increase switching losses and risk shoot-through in half-bridge configurations.

Does the TO-220FP package require an insulating pad when mounted to a heatsink?

No - the TO-220FP package features an electrically insulated metal tab rated for 2.5 kV RMS isolation. Direct mounting to grounded heatsinks is permitted without thermal pads or mica washers, simplifying mechanical assembly and improving thermal transfer efficiency.

How does the 1200 V rating translate to practical input voltage capability?

The 1200 V V_DS rating supports continuous operation with peak line voltages up to 850 V_AC (e.g., 600 V_AC industrial three-phase rectified), including 50% safety margin for transient overvoltages per IEC 61000-4-5. Derating is not required for standard 400/480 V_AC mains inputs.

STF12N120K5 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: MDmesh™ K5

Package/Case:: TO-220-3 Full Pack

Packaging:: Tube

Product Status:: Active

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 1200 V

Current - Continuous Drain (Id) @ 25°C:: 12A (Tc)

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

Rds On (Max) @ Id, Vgs:: 690mOhm @ 6A, 10V

Vgs(th) (Max) @ Id:: 5V @ 100µA

Gate Charge (Qg) (Max) @ Vgs:: 44.2 nC @ 10 V

Vgs (Max):: ±30V

Input Capacitance (Ciss) (Max) @ Vds:: 1370 pF @ 100 V

FET Feature:: -

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

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220FP

STF12N120K5 FAQ

1.How can I place an order for STF12N120K5 through Aetrix?

Please submit a Request for Quotation (RFQ) for STF12N120K5 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 STF12N120K5 reliable?

The price and inventory of STF12N120K5 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STF12N120K5 is usually 5 days.

3.What payment methods are accepted for STF12N120K5?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STF12N120K5 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STF12N120K5?

STF12N120K5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STF12N120K5 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 STF12N120K5?

For technical support, including STF12N120K5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STF12N120K5 requirements.

6.How does Aetrix verify that STF12N120K5 is sourced from the original manufacturer or authorized distributors?

All STF12N120K5 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 STF12N120K5 meets industry standards.

7.What is the process for return or replacement of STF12N120K5?

All STF12N120K5 units undergo pre-shipment inspection (PSI). If there is an issue with STF12N120K5, 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 STF12N120K5 part is unused and in its original packaging.

Return procedure for STF12N120K5:

1.Submit a request within 90 days.

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

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