STMicroelectronics STFW1N105K3

Overview

STFW1N105K3 from STMicroelectronics is an N-channel SuperMESH3™ Power MOSFET rated for 1050 V drain-source voltage, 8 Ω typical R_DS(on), 1.4 A continuous drain current at T_C = 25 °C, and 60 W total power dissipation in TO-3PF package. It delivers high avalanche robustness (130 mJ single-pulse E_AS), low gate charge (13 nC), and ultra-low output capacitance (15 pF C_oss), targeting high-voltage flyback and resonant converters.

For engineers reviewing the STFW1N105K3 datasheet, STFW1N105K3 pinout, STFW1N105K3 application, or STFW1N105K3 equivalent, key selection criteria include its 1050 V V_DS, TO-3PF thermal resistance (R_thj-case = 2.08 °C/W), 100% avalanche testing, and suitability for unclamped inductive switching in industrial SMPS.

Technical Context

This device employs ST's optimized vertical SuperMESH3™ structure to achieve low R_DS(on) while maintaining high breakdown voltage and superior dynamic performance. Its gate threshold voltage (2–4.5 V) enables standard 10 V gate drive compatibility, and intrinsic gate resistance (18 Ω) supports predictable switching behavior under controlled dV/dt conditions.

The MOSFET features a fast source-drain diode with t_rr = 244–330 ns and Q_rr = 1–1.3 μC, enabling efficient hard-switched topologies. Its safe operating area (SOA) is defined up to 1050 V and 5.6 A pulsed current, with thermal limits governed by junction-to-case resistance of 2.08 °C/W in TO-3PF.

Key Specifications

Pinout & Package

STFW1N105K3 is housed in TO-3PF package: insulated metal tab with three leads in inline configuration (Drain, Gate, Source). The metal tab is electrically connected to Drain and serves as primary heat sink interface. Insulation withstand voltage is 3500 V_RMS between leads and heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STP1N105K3, STFW1N105K3 offers 3× better thermal resistance and integrated 3500 V_RMS isolation; versus FQP1N105, it delivers 33% lower R_DS(on), 32% less Q_g, and guaranteed avalanche ruggedness-critical for industrial-grade SMPS.

Availability

STFW1N105K3 is available at Aetrix Electronics and suitable for industrial flyback converters, AC/DC adapters for appliances, and LED driver power supplies requiring stable component supply across multi-year production cycles.

Supply support for STFW1N105K3 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

STFW1N105K3 belongs to the SuperMESH3™ Power MOSFET product line, engineered specifically for high-voltage, high-reliability switching in offline SMPS, UPS, and lighting systems where avalanche ruggedness and thermal efficiency are critical.

FAQ

What is the maximum continuous drain current for STFW1N105K3 at 100 °C case temperature?

The maximum continuous drain current is 0.9 A at T_C = 100 °C, as specified in Table 2 of the datasheet. This derating reflects thermal limitations of the TO-3PF package at elevated temperatures and must be applied in thermal design calculations for sustained operation.

Does STFW1N105K3 require a gate resistor for safe operation?

Yes-a gate resistor is required to control dI/dt and prevent oscillation. The datasheet recommends R_G = 4.7 Ω for switching time characterization (Table 6); values between 2.2 Ω and 10 Ω are typical, balancing speed against ringing and EMI in actual layouts.

Can STFW1N105K3 replace STF1N105K3 in existing TO-220FP designs?

No-STFW1N105K3 uses TO-3PF packaging with different pin spacing, thermal interface, and insulation properties. Direct replacement requires mechanical redesign, heatsink requalification, and verification of creepage/clearance distances due to the 3500 V_RMS isolation rating.

What is the significance of the "K3" suffix in STFW1N105K3?

The "K3" suffix denotes the third-generation SuperMESH™ technology (SuperMESH3™), indicating process enhancements over K1/K2 variants-including reduced R_DS(on), lower gate charge, and improved avalanche energy rating-verified in the January 2013 revision of Doc ID 023509.