STMicroelectronics STB9NK70ZT4

Overview

STB9NK70ZT4 from STMicroelectronics is a Zener-protected N-channel SuperMESH Power MOSFET rated for 700 V drain-source voltage, 1.2 Ω max R_DS(on) at 10 V_GS, and 7.5 A continuous drain current at T_C = 25 °C. It delivers high dv/dt capability (4.5 V/ns), 100% avalanche tested performance, and gate charge minimized for fast switching in offline SMPS and lighting ballasts.

For engineers reviewing the STB9NK70ZT4 datasheet, STB9NK70ZT4 pinout, STB9NK70ZT4 application, or STB9NK70ZT4 equivalent, key selection criteria include its TO-220FP package thermal resistance (R_thJC = 3.6 °C/W), unclamped inductive avalanche rating (E_AS = 230 mJ), and Zener-protected gate enabling robust gate drive in noisy high-voltage environments.

Technical Context

This device implements ST's SuperMESH process - an evolution of PowerMESH - to reduce on-resistance while preserving ruggedness. Its Zener-protected gate structure clamps transient overvoltage to ±30 V, and its optimized layout ensures stable operation under extreme dv/dt stress up to 4.5 V/ns during inductive turn-off.

The MOSFET supports unclamped inductive switching with guaranteed single-pulse avalanche energy of 230 mJ at V_DD = 50 V and I_AR = 7.5 A. Its output capacitance (C_oss = 143 pF) and reverse transfer capacitance (C_rss = 32 pF) are tuned for low EMI in high-frequency flyback and resonant converters.

Key Specifications

Pinout & Package

STB9NK70ZT4 is housed in a TO-220FP (Type B) package - a fully insulated, through-hole variant with internal isolation between leads and heat sink surface (V_ISO = 2.5 kV RMS). The plastic body provides creepage/clearance compliance for reinforced insulation in Class II systems.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STP9NK70ZFP, STB9NK70ZT4 shares identical silicon and packaging but reflects older ST marking convention; versus FQP9N70, it offers superior ruggedness, lower switching losses, and integrated gate protection - critical for reliability in safety-critical offline power supplies.

Availability

STB9NK70ZT4 is available at Aetrix Electronics and suitable for LED streetlight drivers, industrial PLC power supplies, and UV-C disinfection lamp ballasts requiring stable component supply and long-term manufacturability.

Supply support for STB9NK70ZT4 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 microcontrollers, power devices, sensors, and analog ICs for automotive, industrial, and consumer markets.

STB9NK70ZT4 belongs to ST's SuperMESH Power MOSFET product line, engineered specifically for high-efficiency, high-reliability offline AC-DC conversion in space-constrained and thermally demanding applications.

FAQ

Is STB9NK70ZT4 RoHS-compliant and halogen-free?

Yes. STB9NK70ZT4 is manufactured in ST's ECOPACK2-compliant TO-220FP package, meeting RoHS Directive 2011/65/EU and IEC 61249-2-21:2011 for brominated flame retardants. Lead finish is matte tin, and all materials are fully traceable per ST's environmental policy.

What is the maximum safe operating frequency for STB9NK70ZT4 in a flyback converter?

Based on its 68 nC total gate charge and 32 pF Crss, STB9NK70ZT4 supports reliable operation up to 130 kHz in QR flyback designs with proper gate drive strength (≥1 A peak). At 100 kHz, typical switching losses remain below 1.2 W with 10 Ω gate resistor and 12 V drive.

Can STB9NK70ZT4 replace STW9NK70Z in a TO-247-based design?

No. STW9NK70Z uses TO-247 package with higher thermal capability (R_thJC = 1.5 °C/W) and 9 A rating. STB9NK70ZT4 in TO-220FP has lower current and thermal limits. Direct replacement risks thermal runaway above 5 A continuous load; redesign with heatsink and layout review is required.

Does STB9NK70ZT4 require a negative gate voltage for turn-off in high-noise environments?

No. Its Zener-protected gate operates reliably with 0 V to 10 V gate drive. The integrated ±30 V clamp prevents damage from positive or negative transients, eliminating need for negative bias - simplifying gate driver design in EMI-prone industrial settings.