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

STMicroelectronics IRF634

Name: IRF634
Brand: STMicroelectronics
SKU: IRF634
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: IRF634

Manufacturer:: STMicroelectronics

Category:: FETs, MOSFETs

Package:: TO-220-3

Datasheet:: IRF634.pdf

Description:: MOSFET N-CH 250V 8A TO220AB

Quantity:: RFQ Add To RFQ list

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Inventory:9,006

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Product details

Overview

IRF634 from STMicroelectronics is an N-channel enhancement-mode power MOSFET in TO-220 package, rated for 250 V drain-source voltage, 0.38 Ω typical R_DS(on) at V_GS = 10 V, and 8 A continuous drain current at T_C = 25°C. It features 100% avalanche tested ruggedness, 5 V/ns peak diode recovery dv/dt capability, and is designed for high-reliability switching in lighting ballasts and offline SMPS.

For engineers reviewing the IRF634 datasheet, IRF634 pinout, IRF634 application, or IRF634 equivalent, key selection considerations include its 250 V blocking rating, thermal resistance of 1.56 °C/W (juncton-to-case), unclamped inductive switching robustness, and suitability for hard-switched flyback and resonant converter topologies requiring high-voltage MOSFETs with proven avalanche endurance.

Technical Context

This MOSFET employs ST's proprietary MESH OVERLAY™ process and STrip layout, enabling high dv/dt immunity and stable operation under fast transient conditions. Its edge termination structure supports reliable operation up to 150°C junction temperature and withstands repetitive unclamped inductive energy up to 300 mJ per pulse.

The device integrates a built-in body diode with 198 ns reverse recovery time (T_j = 150°C) and 11.3 A peak reverse recovery current, making it suitable for applications where synchronous rectification is not used but diode conduction occurs during dead-time intervals.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DSS	250 V - Supports primary-side switching in universal-input offline converters up to 265 VAC mains.
R_DS(on) max	0.45 Ω - Limits conduction loss to ≤28.8 W at 8 A DC, requiring heatsinking for sustained operation.
I_D cont @ T_C=25°C	8 A - Enables use in 100–200 W power stages without paralleling devices.
E_AS	300 mJ - Withstands single-pulse inductive energy from 50 V bus without failure, critical for flyback snubberless designs.
dv/dt rating	5 V/ns - Ensures immunity to false turn-on during high-slew-rate voltage transients in half-bridge or LLC resonant circuits.
Q_g	37 nC - Determines gate drive power requirement (~3.7 mW at 100 kHz, V_GS swing = 10 V).
R_thj-case	1.56 °C/W - Requires minimum 12 cm² copper area (2 oz) or external heatsink to maintain T_j < 150°C at full load.

Pinout & Package

IRF634 uses standard TO-220 package with 3-pin vertical mounting configuration. Pin 1 is Gate, Pin 2 is Drain (tab-connected), and Pin 3 is Source. The metal tab is electrically connected to the Drain terminal and must be isolated from heatsink unless circuit topology permits common-drain configuration.

Pin/Terminal	Circuit Role	Design Meaning
1 (Gate)	Control input	Receives 10 V logic-level signal to fully enhance channel; requires ≥10 V for specified R_DS(on).
2 (Drain)	High-side switched node	Connected to metal tab; carries full load current and high-voltage switching node-requires creepage clearance and isolation.
3 (Source)	Reference return path	Serves as local ground reference for gate drive; source inductance directly impacts switching speed and ringing.

Key Features

Feature	Design Value
100% avalanche tested	Guarantees single-pulse E_AS = 300 mJ and repetitive I_AR = 8 A, eliminating need for external clamping in cost-sensitive flyback designs.
High dv/dt immunity	5 V/ns rating prevents spurious turn-on during fast voltage transitions in half-bridge or resonant topologies.
MESH OVERLAY™ process	Delivers uniform cell distribution and reduced hot-spot risk under high-current pulsed loads.
TO-220 mechanical robustness	Supports >10⁵ thermal cycles and 300°C lead-soldering tolerance for through-hole manufacturing reliability.

Applications

Compact Fluorescent Lamp (CFL) Ballast

Offline Flyback SMPS

Use Scenario: High-frequency (20–60 kHz) half-bridge inverter driving resonant LC tank for lamp ignition and regulation.

IC Role / Device Role / Timing Role: Primary-side high-voltage switch handling 250 V DC bus and delivering 20–30 W output.

Use Value: Avalanche ruggedness eliminates need for snubber networks, reducing BOM count and board space in cost-sensitive consumer lighting.

Use Scenario: Primary-side switch in universal-input (85–265 VAC), 30–60 W AC/DC adapter with no optocoupler feedback.

IC Role / Device Role / Timing Role: Hard-switched MOSFET operating at 65–100 kHz with discontinuous conduction mode (DCM).

Use Value: Low Q_g (37 nC) enables efficient drive with low-cost bipolar gate drivers, while 250 V rating accommodates reflected output voltage plus leakage spikes.

LED Driver (Non-Isolated Buck-PFC)

Industrial Motor Control (Low-Power)

Use Scenario: Active PFC stage in 40–70 W LED streetlight driver using boost topology with digital controller.

IC Role / Device Role / Timing Role: Switching element in continuous conduction mode (CCM) boost converter operating at 50–100 kHz.

Use Value: Stable R_DS(on) over temperature ensures predictable efficiency across ambient range (–25°C to +85°C), simplifying thermal design.

Use Scenario: Half-bridge leg in 100–200 W brushless DC motor driver for HVAC blowers or small pumps.

IC Role / Device Role / Timing Role: Low-side or high-side switch in 6–24 V DC bus systems with PWM frequencies up to 20 kHz.

Use Value: Fast turn-off (16 ns fall time) and low C_oss (118 pF) minimize switching losses during commutation, improving torque ripple performance.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
STP2NK60Z	600 V V_DSS, 4.5 Ω R_DS(on), 2 A I_D - higher voltage rating but lower current and higher on-resistance.	Better suited for 380 V DC bus PFC stages; not recommended for 250 V/8 A switching due to excessive conduction loss.	Select only if system requires >400 V blocking and can accept derated current handling.
FQP27P06	P-channel, –60 V V_DSS, –27 A I_D, 0.045 Ω R_DS(on) - complementary polarity and lower voltage rating.	Used in high-side load switches or level-shifted gate drivers; incompatible for direct replacement in N-channel topologies.	Only viable in circuits where gate drive architecture supports P-channel high-side configuration and voltage requirements align.

Compared with STP2NK60Z and FQP27P06, IRF634 offers optimal balance of 250 V rating, 8 A current capability, and 0.38 Ω on-resistance for cost-sensitive, medium-power offline converters-neither alternative matches its combination of voltage headroom, current capacity, and thermal performance in TO-220 form factor.

Availability

IRF634 is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, offline flyback SMPS, non-isolated LED drivers, and low-power industrial motor control requiring stable component supply and long-lifecycle support.

Supply support for IRF634 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 industrial, automotive, and consumer markets.

IRF634 belongs to ST's high-voltage power MOSFET product line, engineered specifically for rugged, cost-effective switching in lighting, power supply, and motor control applications where avalanche reliability and manufacturability are critical.

FAQ

Is IRF634 suitable for 230 VAC input rectified applications?

Yes. With a 250 V V_DSS rating and 300 mJ single-pulse avalanche energy, IRF634 safely handles the ~325 VDC peak from 230 VAC rectification plus margin for surge and ringing. Its 150°C max junction temperature and 1.56 °C/W thermal resistance allow stable operation when properly heatsinked in continuous conduction mode.

What is the maximum gate-source voltage for IRF634?

The absolute maximum V_GS is ±20 V. Operation above +20 V risks permanent gate oxide damage; below –20 V may cause threshold shift or latch-up. For reliable enhancement, apply 10 V to achieve the specified 0.38 Ω R_DS(on). Gate drive circuits must include clamping (e.g., Zener diodes) to prevent overshoot beyond this limit.

Does IRF634 have a built-in body diode, and what are its characteristics?

Yes. IRF634 integrates a parasitic N-channel body diode with forward voltage of 1.7 V at 8 A and reverse recovery time of 198 ns at T_j = 150°C. Its Q_rr is 1.1 nC and I_RRM is 11.3 A. These values indicate moderate softness-suitable for non-synchronous topologies but not optimized for zero-voltage switching (ZVS) without external snubbing.

Can IRF634 replace IRF640 in existing designs?

No. Although both are TO-220 N-channel MOSFETs, IRF640 has 500 V V_DSS and 0.18 Ω R_DS(on), while IRF634 is rated for only 250 V and has higher on-resistance. Substituting IRF634 into a 400 V bus design risks avalanche breakdown. It may be used only if the application operates ≤250 V DC and thermal design accommodates higher conduction loss.

IRF634 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: MESH OVERLAY™

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 250 V

Current - Continuous Drain (Id) @ 25°C:: 8A (Tc)

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

Rds On (Max) @ Id, Vgs:: 450mOhm @ 4A, 10V

Vgs(th) (Max) @ Id:: 4V @ 250µA

Gate Charge (Qg) (Max) @ Vgs:: 51.8 nC @ 10 V

Vgs (Max):: ±20V

Input Capacitance (Ciss) (Max) @ Vds:: 770 pF @ 25 V

FET Feature:: -

Power Dissipation (Max):: 80W (Tc)

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

IRF634 FAQ

1.How can I place an order for IRF634 through Aetrix?

Please submit a Request for Quotation (RFQ) for IRF634 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 IRF634 reliable?

The price and inventory of IRF634 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for IRF634 is usually 5 days.

3.What payment methods are accepted for IRF634?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for IRF634 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for IRF634?

IRF634 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your IRF634 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 IRF634?

For technical support, including IRF634 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your IRF634 requirements.

6.How does Aetrix verify that IRF634 is sourced from the original manufacturer or authorized distributors?

All IRF634 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 IRF634 meets industry standards.

7.What is the process for return or replacement of IRF634?

All IRF634 units undergo pre-shipment inspection (PSI). If there is an issue with IRF634, 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 IRF634 part is unused and in its original packaging.

Return procedure for IRF634:

1.Submit a request within 90 days.

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

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