STMicroelectronics STF6NK70Z

Overview

STF6NK70Z from STMicroelectronics is an N-channel 700 V, 1.5 Ω (typ), 5 A Zener-protected SuperMESH™ Power MOSFET in TO-220FP package, designed for high-voltage switching in offline SMPS, AC-DC adapters, and lighting ballasts. It features 100% avalanche rating, 4.5 V/ns dv/dt capability, and integrated gate-source Zener protection.

For engineers reviewing the STF6NK70Z datasheet, STF6NK70Z pinout, STF6NK70Z application, or STF6NK70Z equivalent, key selection criteria include R_DS(on) stability at T_C = 100°C, unclamped inductive switching robustness, thermal resistance (R_thj-case = 4.2 °C/W), and ESD immunity (4 kV HBM).

Technical Context

This MOSFET employs ST's strip-based SuperMESH™ layout to minimize R_DS(on) while preserving high dv/dt immunity and low intrinsic capacitances (C_iss = 930 pF, C_oss = 105 pF). Its gate charge profile (Q_g = 34 nC, Q_gd = 17 nC) supports efficient hard-switching up to 100 kHz in flyback and resonant topologies.

The integrated back-to-back gate-source Zener diodes (BVGSO = 30 V) provide intrinsic overvoltage clamping without external components, enhancing system reliability during gate drive transients and ESD events. Avalanche energy rating (E_AS = 200 mJ) enables safe operation under unclamped inductive load conditions.

Key Specifications

Pinout & Package

STF6NK70Z uses the TO-220FP (Full-Pak) package: insulated plastic case with internal heat sink tab, 3-pin vertical mounting, lead-free ECOPACK® compliant construction. Thermal pad is electrically connected to drain (Pin 2).

Key Features

Applications

Equivalent & Alternatives

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

Compared with STP6NK70Z, STF6NK70Z trades thermal resistance for electrical isolation and compact footprint; versus FDPF18N50, it delivers critical 700 V rating and built-in gate protection essential for robust offline SMPS design.

Availability

STF6NK70Z is available at Aetrix Electronics and suitable for offline flyback SMPS, LED lighting ballasts, and industrial auxiliary power supplies requiring stable component supply across multi-year production cycles.

Supply support for STF6NK70Z 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, sensors, and automotive ICs.

STF6NK70Z belongs to the SuperMESH™ high-voltage MOSFET product line, engineered specifically for rugged, high-efficiency switching in universal-input AC-DC conversion and lighting control systems.

FAQ

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

The STF6NK70Z supports 3.15 A continuous drain current at T_C = 100°C, as specified in Table 1 of the datasheet. This derated value reflects thermal limitations of the TO-220FP package (R_thj-case = 4.2 °C/W) and ensures safe operation within the 150°C maximum junction temperature limit.

Does STF6NK70Z require an external gate resistor for EMI suppression?

Yes - although the device integrates gate-source Zener protection, a series gate resistor (typically 10–47 Ω) is required to dampen ringing, control dV/dt, and limit peak gate current during switching transitions. The recommended value depends on driver strength and layout parasitics, per Figure 18 test circuit.

Can STF6NK70Z replace STP6NK70Z in existing designs?

Electrically yes, but mechanically no - both share identical V_DSS, R_DS(on), and avalanche ratings, but STF6NK70Z uses TO-220FP (insulated tab), whereas STP6NK70Z uses standard TO-220 (conductive tab). PCB footprint and heatsink isolation must be re-evaluated before substitution.

Is the 2500 V_RMS insulation rating certified to any safety standard?

The 2500 V_RMS insulation withstand voltage (measured from all three leads to external heat sink, t = 1 s, T_C = 25°C) meets basic insulation requirements per IEC 60747-5-2 and supports reinforced isolation when combined with appropriate creepage/clearance in PCB layout and transformer design.