STMicroelectronics STFI5N95K3

Overview

STFI5N95K3 from STMicroelectronics is an N-channel 950 V, 3.5 Ω max, 4 A Zener-protected SuperMESH3™ Power MOSFET in I2PAKFP (TO-281) package. It delivers high avalanche ruggedness (100 mJ single-pulse), low gate charge (19 nC), and integrated gate-source Zener protection (±30 V), making it suitable for high-voltage flyback and resonant switching converters in industrial power supplies.

For engineers reviewing the STFI5N95K3 datasheet, STFI5N95K3 pinout, STFI5N95K3 application, or STFI5N95K3 equivalent, key selection criteria include its 950 V breakdown voltage, 5 °C/W junction-to-case thermal resistance, 460 pF input capacitance, and Zener-protected gate enabling robust gate drive in noisy high-dV/dt environments.

Technical Context

This device employs ST's optimized vertical SuperMESH3™ structure to achieve ultra-low R_DS(on) while maintaining high voltage capability and superior dynamic performance. Its internal back-to-back Zener diodes clamp gate-source transients up to ±30 V, eliminating external gate protection components.

The MOSFET features extremely low intrinsic capacitances (C_iss = 460 pF, C_oss = 38 pF) and fast switching (t_d(off) = 32 ns, t_f = 18 ns), enabling high-frequency operation in hard-switched topologies without sacrificing SOA integrity or avalanche reliability.

Key Specifications

Pinout & Package

The STFI5N95K3 is housed in an insulated I2PAKFP (TO-281) package with creepage-enhanced leadframe and integral heatsink plate. The package provides 2500 V_RMS insulation between leads and heatsink, supporting reinforced isolation in safety-critical power stages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STP5NK90Z and IXTP5N90P, the STFI5N95K3 offers superior 950 V rating, integrated Zener protection, lower gate charge, and better thermal performance-making it optimal for new designs prioritizing reliability, miniaturization, and reduced component count in high-noise industrial environments.

Availability

STFI5N95K3 is available at Aetrix Electronics and suitable for industrial flyback converters, LED driver power stages, AC-DC adapters, and UPS inverter stages requiring stable component supply and long-term manufacturing continuity.

Supply support for STFI5N95K3 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.

The SuperMESH3™ Power MOSFET product line targets high-efficiency, high-reliability offline power conversion, emphasizing avalanche ruggedness, low R_DS(on), and integrated protection for demanding industrial and infrastructure applications.

FAQ

What is the maximum allowable gate-source voltage for STFI5N95K3?

The STFI5N95K3 features integrated back-to-back Zener diodes with a rated gate-source breakdown voltage of ±30 V (I_GS = ±1 mA). This clamps transients automatically, allowing safe operation with gate drive voltages up to ±20 V under normal conditions and transient spikes up to ±30 V without external protection components.

Can STFI5N95K3 replace STP5NK90Z in existing designs?

Direct replacement is not recommended without layout and thermal review. While both are 900+ V N-channel MOSFETs, STFI5N95K3 uses I2PAKFP (TO-281) with insulated heatsink contact and integrated Zener, whereas STP5NK90Z uses TO-220 without insulation or gate protection. PCB footprint, gate drive design, and heatsink isolation must be revalidated.

What is the safe operating area (SOA) limitation at 100 °C case temperature?

At T_C = 100 °C, the continuous drain current is derated to 3 A (per Table 2), and pulsed current remains limited to 16 A (IDM) with pulse width constrained by SOA boundaries. The device maintains full 950 V blocking capability, but power dissipation must stay below 12.5 W to avoid exceeding the 150 °C maximum junction temperature.

Does STFI5N95K3 require a gate resistor for EMI suppression?

A gate resistor is required for controlled switching and EMI management. Typical values range from 4.7 Ω to 22 Ω depending on switching speed requirements. The datasheet specifies t_d(on)/t_d(off) test conditions using R_G = 4.7 Ω; increasing resistance slows transitions, reducing EMI but raising switching losses-designers must balance this trade-off per application frequency and thermal constraints.