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

STMicroelectronics STY34NB50

Name: STY34NB50
Brand: STMicroelectronics
SKU: STY34NB50
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STY34NB50

Manufacturer:: STMicroelectronics

Category:: FETs, MOSFETs

Package:: TO-247-3

Datasheet:: STY34NB50.pdf

Description:: MOSFET N-CH 500V 34A MAX247

Quantity:: RFQ Add To RFQ list

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Inventory:3,950

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Product details

Overview

STY34NB50 from STMicroelectronics is an N-channel enhancement-mode PowerMESH™ MOSFET rated for 500 V drain-source voltage, 34 A continuous drain current at T_c = 25 °C, and typical R_DS(on) of 0.11 Ω. It features ±30 V gate-source voltage rating, 100% avalanche tested operation, and high dv/dt capability (4.5 V/ns), designed for high-speed switching in industrial power conversion stages.

For engineers reviewing the STY34NB50 datasheet, STY34NB50 pinout, STY34NB50 application, or STY34NB50 equivalent, key selection criteria include its Max247™ TO-247AC package thermal resistance (R_thj-case = 0.277 °C/W), low gate charge (Q_g = 159 nC), and unclamped inductive switching robustness under 34 A repetitive avalanche conditions.

Technical Context

This MOSFET employs ST's proprietary MESH OVERLAY™ process with strip layout and edge termination to minimize R_DS(on) per die area and maximize dv/dt immunity. Its intrinsic capacitances-C_iss = 7000 pF, C_oss = 950 pF, C_rss = 80 pF-are optimized for fast switching with reduced Miller effect.

The device supports hard-switched topologies with guaranteed unclamped inductive switching (UIS) up to E_AS = 1000 mJ at T_j = 25 °C and operates safely up to T_j = 150 °C. Its source-drain diode exhibits t_rr = 950 ns and Q_rr = 12 µC under specified di/dt and temperature conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DSS	500 V - supports primary-side switching in offline SMPS up to 400 V DC bus with margin
R_DS(on) typ.	0.11 Ω - enables <1.2 W conduction loss at 34 A, reducing heatsink requirements
I_D cont. @ T_c=25°C	34 A - rated for high-current output stages in welding inverters and UPS systems
Q_g	159 nC - lowers gate drive power and enables use with standard 1–2 A peak gate drivers
dv/dt max	4.5 V/ns - sustains rapid voltage transients without spurious turn-on in noisy EMI environments
E_AS	1000 mJ - withstands single-pulse inductive energy without failure in motor drive freewheeling
R_thj-case	0.277 °C/W - allows direct mounting to heatsink with minimal thermal interface resistance

Pinout & Package

STY34NB50 is housed in a Max247™ (TO-247AC) package with isolated tab, featuring three terminals: Drain (case), Source (pin 1), and Gate (pin 2). The metal tab is electrically connected to the Drain, requiring insulating mounting hardware when used in non-isolated configurations.

Pin/Terminal	Circuit Role	Design Meaning
Drain (Tab)	Main high-voltage current path collector	Electrically tied to case; must be insulated from heatsink unless system ground reference permits
Source (Pin 1)	Reference node for gate control and current return	Low-inductance connection point for gate driver return and sense resistor placement
Gate (Pin 2)	Control electrode for channel modulation	Requires <±30 V drive; sensitive to ringing due to low C_rss (80 pF) and high g_fs (18 S)

Key Features

Feature	Design Value
PowerMESH™ structure	Reduces R_DS(on) per unit area by >25% vs. conventional planar HV MOSFETs, improving power density
100% UIS tested	Guarantees operation under unclamped inductive load stress up to 34 A, eliminating need for external snubbers in many cases
Low C_rss / C_iss ratio	80 pF / 7000 pF = 0.011 - minimizes Miller-induced gate oscillation during high di/dt switching
High T_j rating	150 °C maximum junction temperature - supports operation in sealed enclosures or high-ambient industrial environments
Low V_SD	1.6 V forward drop at 34 A - reduces reverse-conduction losses in synchronous rectification or half-bridge freewheeling

Applications

Welding Inverter Primary Switch

UPS DC-AC Inverter Stage

Use Scenario: High-frequency (20–50 kHz) hard-switched IGBT replacement in portable arc welders with 400 V DC bus.

IC Role / Device Role / Timing Role: Main switching element in full-bridge topology handling 34 A peak load current with 500 V blocking.

Use Value: Low R_DS(on) and high dv/dt immunity reduce switching losses and eliminate false triggering during arc initiation transients.

Use Scenario: Output stage switch in online double-conversion UPS delivering 3 kVA with sine-wave synthesis.

IC Role / Device Role / Timing Role: High-side switch in H-bridge inverter leg operating at 16 kHz PWM with bidirectional current capability.

Use Value: Avalanche ruggedness ensures reliability during grid-synchronization transients and load dump events without derating.

Industrial Motor Drive Inverter

SMPS Primary-Side Switch

Use Scenario: 7.5 kW variable-frequency drive for HVAC compressors using six-pack IGBT module replacement.

IC Role / Device Role / Timing Role: Phase-leg low-side switch conducting 34 A RMS with 150 °C junction temperature limit.

Use Value: Low gate charge (159 nC) enables efficient gate driving with integrated 2 A drivers, reducing external component count.

Use Scenario: 1 kW flyback or LLC resonant converter in telecom rectifier with universal AC input.

IC Role / Device Role / Timing Role: Primary-side switching transistor in discontinuous conduction mode (DCM) operation.

Use Value: Tight R_DS(on) distribution (<0.13 Ω max) ensures consistent efficiency across production batches and temperature range.

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
STW34NB50	Same die, TO-247 long leads (not Max247); R_thj-case = 0.33 °C/W vs. 0.277 °C/W	Slightly lower thermal performance; requires larger heatsink footprint for same power dissipation	Select when legacy board layout uses standard TO-247 footprint and thermal margin ≥15% exists
IPP50R110CFD7	650 V SiC MOSFET, R_DS(on) = 0.11 Ω, Q_g = 42 nC, but higher gate threshold (3.5 V min)	Enables >100 kHz operation with lower switching loss, but requires gate driver redesign for higher V_GS and negative turn-off	Select only when upgrading to >80 kHz switching frequency and revalidating gate drive loop stability

Compared with STW34NB50, STY34NB50 delivers superior thermal transfer via Max247 packaging; versus IPP50R110CFD7, it offers plug-in compatibility with existing 10 V gate drivers and proven avalanche behavior in legacy 20–50 kHz designs.

Availability

STY34NB50 is available at Aetrix Electronics and suitable for welding inverters, uninterruptible power supplies, and industrial motor drives requiring stable component supply and long-term industrial lifecycle support.

Supply support for STY34NB50 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 and discrete power devices for industrial, automotive, and consumer markets.

The STY34NB50 belongs to ST's PowerMESH™ HV MOSFET product line, engineered specifically for ruggedized high-voltage switching in industrial power conversion where avalanche reliability and thermal efficiency are critical.

FAQ

Is STY34NB50 still in active production?

No - STY34NB50 is marked "Obsolete Product(s)" in the official ST datasheet revision (June 1998). However, Aetrix Electronics maintains legacy inventory with full traceability and provides engineering support for design-in continuity in maintenance and replacement programs.

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

At T_c = 100 °C, the continuous drain current is derated to 21.4 A. The SOA curve (Figure 7 in datasheet) shows that pulsed operation remains limited to 136 A for ≤100 µs pulses, with V_DS ≤ 500 V and duty cycle ≤ 1.5% to avoid secondary breakdown.

Can STY34NB50 be used in synchronous rectification?

Yes - its source-drain diode has V_SD = 1.6 V at 34 A and t_rr = 950 ns, making it viable for low-frequency synchronous rectification (≤50 kHz) in flyback or forward converters where body diode conduction is unavoidable during dead-time.

Does STY34NB50 require negative gate turn-off voltage?

No - the device is fully compatible with 0 V to +10 V or +15 V gate drive. Its ±30 V V_GS rating allows optional –5 V to –10 V turn-off for noise immunity, but it is not required; standard TTL/CMOS-compatible drivers suffice for most applications.

STY34NB50 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: PowerMESH™

Package/Case:: TO-247-3

Packaging:: Tube

Product Status:: Obsolete

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 500 V

Current - Continuous Drain (Id) @ 25°C:: 34A (Tc)

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

Rds On (Max) @ Id, Vgs:: 130mOhm @ 17A, 10V

Vgs(th) (Max) @ Id:: 5V @ 250µA

Gate Charge (Qg) (Max) @ Vgs:: 223 nC @ 10 V

Vgs (Max):: ±30V

Input Capacitance (Ciss) (Max) @ Vds:: 9100 pF @ 25 V

FET Feature:: -

Power Dissipation (Max):: 450W (Tc)

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: MAX247™

STY34NB50 FAQ

1.How can I place an order for STY34NB50 through Aetrix?

Please submit a Request for Quotation (RFQ) for STY34NB50 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 STY34NB50 reliable?

The price and inventory of STY34NB50 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STY34NB50 is usually 5 days.

3.What payment methods are accepted for STY34NB50?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STY34NB50 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STY34NB50?

STY34NB50 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STY34NB50 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 STY34NB50?

For technical support, including STY34NB50 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STY34NB50 requirements.

6.How does Aetrix verify that STY34NB50 is sourced from the original manufacturer or authorized distributors?

All STY34NB50 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 STY34NB50 meets industry standards.

7.What is the process for return or replacement of STY34NB50?

All STY34NB50 units undergo pre-shipment inspection (PSI). If there is an issue with STY34NB50, 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 STY34NB50 part is unused and in its original packaging.

Return procedure for STY34NB50:

1.Submit a request within 90 days.

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

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