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Home > Products > Discrete Semiconductor Products > Transistors > FETs, MOSFETs > FETs, MOSFETs

STMicroelectronics STW20NK70Z

Name: STW20NK70Z
Brand: STMicroelectronics
SKU: STW20NK70Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STW20NK70Z

Manufacturer:: STMicroelectronics

Category:: FETs, MOSFETs

Package:: TO-247-3

Datasheet:: STW20NK70Z.pdf

Description:: MOSFET N-CH 700V 20A TO247-3

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Inventory:5,858

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Product details

Overview

STW20NK70Z from STMicroelectronics is a Zener-protected N-channel SuperMESH™ power MOSFET rated for 700 V drain-source voltage, 0.25 Ω typical R_DS(on), and 20 A continuous drain current at T_C = 25°C in TO-247 package. It features built-in gate-source Zener diodes (±30 V), 100% avalanche tested (E_AS = 300 mJ), and optimized for high-speed, high-current switching in offline SMPS primary-side circuits.

For engineers reviewing the STW20NK70Z datasheet, STW20NK70Z pinout, STW20NK70Z application, or STW20NK70Z equivalent, key selection criteria include its 4.5 V/ns dv/dt capability, low C_oss,eq (310 pF), minimized gate charge (Q_g = 185 nC), and integrated Zener protection eliminating external clamping components.

Technical Context

This MOSFET employs ST's strip-based SuperMESH™ layout to simultaneously reduce R_DS(on) and enhance dynamic ruggedness. Its gate-source Zener diodes (V_Z = ±30 V) provide intrinsic overvoltage protection during fast transients, while the 100% unclamped inductive avalanche test ensures robustness under hard-switching fault conditions.

The device delivers 350 W total dissipation at T_C = 25°C with R_thj-case = 0.36 °C/W, and exhibits low reverse recovery charge (Q_rr = 16 µC at T_j = 25°C) and fast diode recovery (t_rr = 940 ns), enabling efficient operation in quasi-resonant and hard-switched flyback and forward converters.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DSS	700 V - Withstands full mains-related surge voltages in universal-input offline supplies without derating.
R_DS(on) (typ)	0.25 Ω - Enables <1.25 W conduction loss at 20 A, reducing heatsink requirements in high-power adapters.
I_D (cont, T_C=25°C)	20 A - Supports >300 W output in single-switch flyback topologies with adequate thermal management.
E_AS	300 mJ - Guarantees safe energy absorption during single-pulse inductive switching faults at 50 V bus.
Q_g	185 nC - Low gate drive power demand enables use with standard 1–2 A gate drivers in high-frequency designs.
C_oss,eq	310 pF - Reduces turn-off losses and improves efficiency in resonant and soft-switching applications.
dv/dt capability	4.5 V/ns - Prevents spurious turn-on in high-noise environments such as industrial motor drives and PFC stages.

Pinout & Package

Delivered in TO-247 package (standard 3-lead through-hole power package with isolated tab). Thermal resistance R_thj-case = 0.36 °C/W supports direct mounting to heatsinks.

Pin/Terminal	Circuit Role	Design Meaning
Drain (Tab)	Main high-voltage current path	Electrically connected to metal tab - must be insulated from chassis unless referenced to high-side ground.
Source	Reference node for gate drive and current sensing	Low-inductance return path; used for current-mode control feedback in SMPS controllers.
Gate	Control terminal for channel modulation	Protected by integrated back-to-back Zeners (±30 V); requires no external TVS for typical gate drive circuits.

Key Features

Feature	Design Value
Zener-protected gate	Integrated ±30 V gate-source Zener diodes eliminate need for external clamping, reducing BOM count and PCB area.
100% avalanche tested	Each unit validated for repetitive and non-repetitive unclamped inductive switching up to E_AS = 300 mJ.
Extremely high dv/dt capability	Rated 4.5 V/ns - prevents false triggering in noisy high-voltage switching nodes without snubber networks.
Low intrinsic capacitances	C_iss = 6000 pF, C_oss,eq = 310 pF - minimizes switching losses and improves efficiency above 100 kHz.
SuperMESH™ layout	Optimized strip geometry achieves 0.25 Ω R_DS(on) at 700 V while maintaining manufacturing repeatability and yield.

Applications

AC-DC Power Adapters

Industrial SMPS

Use Scenario: Universal-input (85–265 V_AC) 250–350 W flyback converter for medical and telecom power supplies.

IC Role / Device Role / Timing Role: Primary-side high-voltage switch handling full input rectified voltage and delivering regulated DC output via transformer coupling.

Use Value: 700 V rating avoids series stacking; 0.25 Ω R_DS(on) reduces conduction loss by ~25% vs. legacy 0.33 Ω equivalents at full load.

Use Scenario: 400 W forward converter in programmable logic controller (PLC) power modules operating in harsh ambient (T_A ≤ 70°C).

IC Role / Device Role / Timing Role: Main switching element in primary-side power stage, synchronized to PWM controller with tight dead-time control.

Use Value: 4.5 V/ns dv/dt immunity prevents misfiring during EMI events; 100% avalanche test ensures reliability during line surges.

LED Driver Systems

High-Voltage DC-DC Converters

Use Scenario: Constant-current 150 W LED driver for street lighting using active PFC + LLC topology.

IC Role / Device Role / Timing Role: PFC boost switch operating at 65–100 kHz with high peak current (I_DM = 80 A pulsed).

Use Value: Low Q_g (185 nC) and C_oss,eq (310 pF) enable high-frequency PFC operation with <15 W gate drive loss.

Use Scenario: Isolated 48 V to 380 V DC-DC boost converter in battery energy storage systems (BESS).

IC Role / Device Role / Timing Role: High-side switch in two-switch forward or half-bridge configuration handling 350–400 V DC bus.

Use Value: Built-in Zener protection withstands gate transients from parasitic coupling in high-dV/dt gate loops, avoiding external TVS diodes.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
STW20NK50Z	500 V V_DSS, same R_DS(on) (0.25 Ω), lower E_AS (220 mJ)	Not suitable for 700 V bus designs; limited to 380 V DC-link or 230 V_AC systems with margin	Select only when system max V_DS ≤ 500 V and cost sensitivity outweighs voltage headroom needs.
IPP60R099C6	600 V, 0.099 Ω R_DS(on), CoolMOS™ technology, higher C_oss (420 pF)	Better conduction efficiency below 10 A but higher switching loss above 150 kHz due to C_oss and Q_g (125 nC)	Prefer for high-frequency, medium-power (<200 W) designs where thermal budget allows lower R_DS(on) trade-off.

Compared with STW20NK50Z and IPP60R099C6, STW20NK70Z uniquely balances 700 V ruggedness, low gate charge, and integrated Zener protection-making it optimal for cost-sensitive, high-reliability offline power supplies where voltage margin and transient immunity are critical.

Availability

STW20NK70Z is available at Aetrix Electronics and suitable for AC-DC power adapters, industrial SMPS, LED driver systems, and high-voltage DC-DC converters requiring stable component supply across extended production lifecycles.

Supply support for STW20NK70Z 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, designing and manufacturing analog, digital, and mixed-signal ICs, discrete devices, and MEMS sensors for automotive, industrial, and consumer markets.

This device belongs to ST's SuperMESH™ high-voltage MOSFET product line, engineered specifically for rugged, high-efficiency primary-side switching in offline power conversion systems up to 700 V.

FAQ

Is STW20NK70Z still in active production?

STW20NK70Z is marked as "Obsolete Product(s)" in the official ST datasheet revision (April 2004), indicating it has been discontinued by STMicroelectronics. However, Aetrix Electronics maintains legacy inventory with full traceability and offers extended supply support for ongoing production programs requiring this specific part number.

What is the maximum recommended gate resistor value for reliable switching?

Based on measured t_d(on) = 42 ns and Q_g = 185 nC, a gate resistor of 4.7 Ω (as tested in the datasheet) provides optimal balance between switching speed and ringing suppression. Values above 10 Ω increase turn-on time significantly and may cause thermal stress under high-frequency operation.

Can STW20NK70Z replace STW20NK60Z in existing designs?

Yes - STW20NK70Z is a direct voltage-ruggedized upgrade of STW20NK60Z (600 V), sharing identical pinout, R_DS(on), and thermal characteristics. The 700 V rating provides additional margin for surge-prone applications without circuit modification, though gate drive and snubber design remain unchanged.

Does the integrated Zener protect against negative gate pulses during Miller-induced turn-on?

Yes - the back-to-back Zener structure clamps both positive and negative gate transients to ±30 V. This directly mitigates false turn-on caused by high dv/dt coupling through C_rss, especially during hard commutation in bridge configurations, eliminating need for negative gate drive or external clamp diodes.

STW20NK70Z Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: SuperMESH™

Package/Case:: TO-247-3

Packaging:: Tube

Product Status:: Obsolete

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 700 V

Current - Continuous Drain (Id) @ 25°C:: 20A (Tc)

Drive Voltage (Max Rds On, Min Rds On):: 10V

Rds On (Max) @ Id, Vgs:: 285mOhm @ 10A, 10V

Vgs(th) (Max) @ Id:: 4.5V @ 150µA

Gate Charge (Qg) (Max) @ Vgs:: 185 nC @ 10 V

Vgs (Max):: ±30V

Input Capacitance (Ciss) (Max) @ Vds:: 6000 pF @ 25 V

FET Feature:: -

Power Dissipation (Max):: 350W (Tc)

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-247-3

STW20NK70Z FAQ

1.How can I place an order for STW20NK70Z through Aetrix?

Please submit a Request for Quotation (RFQ) for STW20NK70Z on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for STW20NK70Z reliable?

The price and inventory of STW20NK70Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STW20NK70Z is usually 5 days.

3.What payment methods are accepted for STW20NK70Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STW20NK70Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STW20NK70Z?

STW20NK70Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STW20NK70Z order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for STW20NK70Z?

For technical support, including STW20NK70Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STW20NK70Z requirements.

6.How does Aetrix verify that STW20NK70Z is sourced from the original manufacturer or authorized distributors?

All STW20NK70Z products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that STW20NK70Z meets industry standards.

7.What is the process for return or replacement of STW20NK70Z?

All STW20NK70Z units undergo pre-shipment inspection (PSI). If there is an issue with STW20NK70Z, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The STW20NK70Z part is unused and in its original packaging.

Return procedure for STW20NK70Z:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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