STMicroelectronics STD6NK50ZT4

Overview

STD6NK50ZT4 from STMicroelectronics is a Zener-protected N-channel SuperMESH Power MOSFET rated for 500 V drain-source voltage, 0.93 Ω typical R_DS(on), and 5.6 A continuous drain current at T_C = 25 °C. It delivers high dv/dt capability (4.5 V/ns), 100% avalanche tested operation, and low gate charge (24.6 nC) for hard-switching in offline SMPS and AC-DC adapters.

For engineers reviewing the STD6NK50ZT4 datasheet, STD6NK50ZT4 pinout, STD6NK50ZT4 application, or STD6NK50ZT4 equivalent, key selection criteria include its DPAK package thermal resistance (R_thJC = 1.38 °C/W), intrinsic capacitance profile (C_iss = 690 pF, C_oss = 100 pF), and Zener-protected gate enabling robust ESD immunity (3 kV HBM).

Technical Context

This device implements ST's SuperMESH process - an evolution of PowerMESH - to simultaneously reduce on-resistance and enhance switching ruggedness. Its optimized cell layout yields low output capacitance (C_oss = 100 pF) and reverse transfer capacitance (C_rss = 20 pF), supporting high-frequency operation with minimized Miller effect.

The integrated gate-source Zener diode clamps transients up to ±30 V, eliminating external protection in many designs. Avalanche energy rating (E_AS = 180 mJ) and repetitive avalanche current (I_AR = 5.6 A) confirm suitability for unclamped inductive switching in flyback and resonant converters.

Key Specifications

Pinout & Package

Package: DPAK (TO-252 type C3), surface-mount, thermally enhanced with exposed drain tab (pin 2). Mounting requires minimum 1-inch² 2 oz copper pad for R_thJA = 50 °C/W performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage N-channel MOSFET applications.

Compared with STP6NK50Z and IPP60R190C6, STD6NK50ZT4 uniquely balances DPAK-mountable form factor, integrated Zener protection, and proven avalanche ruggedness - making it optimal for cost-sensitive, space-constrained offline converters requiring zero-failure field reliability.

Availability

STD6NK50ZT4 is available at Aetrix Electronics and suitable for offline AC-DC adapters, flyback SMPS, and industrial LED drivers requiring stable component supply across multi-year production cycles.

Supply support for STD6NK50ZT4 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 automotive, industrial, and consumer markets.

STD6NK50ZT4 belongs to ST's SuperMESH Power MOSFET product line, engineered specifically for high-reliability, high-voltage switching in cost-sensitive offline power conversion systems where avalanche robustness and gate protection are non-negotiable.

FAQ

What is the maximum safe operating temperature for STD6NK50ZT4?

The junction temperature must not exceed 150 °C under steady-state operation. With R_thJC = 1.38 °C/W and 90 W total power dissipation at T_C = 25 °C, proper PCB copper area (≥1-inch² 2 oz) and ambient airflow are required to maintain T_J < 130 °C at full load. Derating curves in Figure 1 of DS3532 define safe current limits above 25 °C case temperature.

Does STD6NK50ZT4 require an external gate resistor for stability?

Yes - a gate resistor (typically 4.7 Ω to 22 Ω) is required to dampen ringing and control switching speed. The datasheet specifies switching times (e.g., t_r = 23.5 ns) with R_G = 4.7 Ω. Omitting this resistor risks oscillation due to low C_rss and high dv/dt, potentially causing shoot-through or gate overvoltage.

Can STD6NK50ZT4 replace STP6NK50Z in existing designs?

Yes, with PCB layout adaptation: both share identical electrical specs and avalanche rating, but STD6NK50ZT4 uses DPAK (surface-mount) versus STP6NK50Z's TO-220 (through-hole). Thermal performance differs - R_thJC is 1.38 °C/W vs 1.0 °C/W - so thermal validation is required if replacing in thermally constrained layouts.

Is the body diode suitable for synchronous rectification?

No - the body diode has t_rr = 254 ns and Q_rr = 1.2 µC at 25 °C, which causes significant reverse recovery loss in high-frequency synchronous rectification. It is intended for freewheeling only in DCM flyback or snubber circuits, not as a primary rectifier. External Schottky or MOSFET synchronous rectifiers are recommended for >100 kHz operation.