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

Vishay Siliconix IRF840S

Name: IRF840S
Brand: Vishay Siliconix
SKU: IRF840S
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: IRF840S

Manufacturer:: Vishay Siliconix

Category:: FETs, MOSFETs

Package:: TO-263-3, D2PAK (2 Leads + Tab), TO-263AB

Datasheet:: IRF840S.pdf

Description:: MOSFET N-CH 500V 8A D2PAK

Quantity:: RFQ Add To RFQ list

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Product details

Overview

IRF840S from Vishay Siliconix is a 500 V, 8.0 A N-channel enhancement-mode power MOSFET in D2PAK (TO-263) surface-mount package, featuring 0.85 Ω R_DS(on) at V_GS = 10 V, 63 nC total gate charge, and repetitive avalanche rating - designed for high-voltage switching in offline SMPS, motor drives, and DC-DC converters.

For engineers reviewing the IRF840S datasheet, IRF840S pinout, IRF840S application, or IRF840S equivalent, this page delivers verified electrical specs, thermal derating behavior, body diode recovery performance (t_rr = 460–970 ns), and real-world PCB-mount power dissipation (3.1 W), enabling accurate thermal design and reliability validation.

Technical Context

The IRF840S employs a third-generation planar vertical DMOS structure optimized for ruggedness and fast switching in high-voltage hard-switched topologies. Its 1.0 °C/W junction-to-case thermal resistance supports high-power density layouts when mounted on copper-clad FR-4 PCBs.

It features dynamic dV/dt immunity up to 3.5 V/ns and is rated for unclamped inductive switching with E_AS = 510 mJ (single-pulse) and I_AR = 8.0 A (repetitive avalanche), enabling robust operation in flyback and forward converter primary switches without external snubbers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	500 V - Supports 400 V DC bus designs with 25 % safety margin for line surges and ringing.
R_DS(on)	0.85 Ω @ V_GS = 10 V - Enables <1.5 W conduction loss at 4.8 A continuous drain current.
Q_g	63 nC - Requires moderate gate drive strength; compatible with standard 1-A peak drivers.
I_D (T_C = 100 °C)	5.1 A - Defines usable current limit under sustained thermal conditions on heatsinked PCBs.
E_AS	510 mJ - Allows safe energy absorption during single-event inductive turn-off transients.
t_rr	460–970 ns - Determines minimum dead-time requirements in half-bridge configurations.
R_thJC	1.0 °C/W - Enables direct thermal coupling to external heatsinks via the exposed drain pad.

Pinout & Package

D2PAK (TO-263) surface-mount package with exposed drain pad for thermal and electrical connection; 3-terminal configuration (G, D, S); lead (Pb)-free and halogen-free compliant per Vishay specification.

Pin/Terminal	Circuit Role	Design Meaning
G (Gate)	Control electrode	Accepts 10 V logic-level drive; ±20 V absolute max rating prevents oxide damage during layout transients.
D (Drain)	High-side power terminal	Exposed metal pad - must be connected to high-voltage DC bus plane for thermal and low-inductance current path.
S (Source)	Reference node / return path	Connected to power ground; source inductance (L_S = 7.5 nH) impacts switching waveform ringing and gate oscillation risk.

Key Features

Feature	Design Value
Repetitive avalanche rated	Rated for 13 mJ per pulse (I_AR = 8.0 A) - eliminates need for external clamping in moderate-energy inductive loads.
Dynamic dV/dt immunity	3.5 V/ns - suppresses false turn-on in high-dV/dt environments like PFC boost stages.
Fast switching	td(on) = 14 ns, tr = 23 ns, td(off) = 49 ns, tf = 20 ns - enables >100 kHz operation with low switching losses.
Low internal inductance	L_D = 4.5 nH, L_S = 7.5 nH - minimizes voltage overshoot and gate ringing in high-speed layouts.
Surface-mount ruggedization	D2PAK package withstands >2.0 W in typical PCB mount - supports compact, no-heat-sink designs up to ~3 W output.

Applications

Offline AC-DC Power Supplies	DC-DC Boost Converters
Use Scenario: Primary-side switch in 50–150 W universal-input flyback converters. IC Role / Device Role / Timing Role: High-voltage switching element controlling energy transfer across transformer; operates at 65–132 kHz with zero-voltage switching assist. Use Value: 500 V rating accommodates 385 V DC link with margin; 0.85 Ω R_DS(on) limits conduction loss to <1.2 W at full load.	Use Scenario: Main switch in isolated DC-DC boost stages for industrial battery charging (24 V → 400 V). IC Role / Device Role / Timing Role: High-side power switch synchronizing with controller PWM; handles 8 A pulsed drain current. Use Value: Repetitive avalanche capability absorbs inductive kickback during fault events without failure.
Motor Drive Half-Bridges	Lighting Ballast Circuits
Use Scenario: Low-side switch in 3-phase BLDC inverter stages for HVAC blowers (≤1 kW). IC Role / Device Role / Timing Role: Fast-turning N-channel switch paired with complementary high-side driver; manages 5.1 A continuous phase current. Use Value: 63 nC Q_g enables efficient gate driving with integrated half-bridge ICs (e.g., IR2104).	Use Scenario: Resonant switch in electronic CFL/LED ballasts operating at 25–50 kHz. IC Role / Device Role / Timing Role: Hard-switched resonant transistor managing high dv/dt transitions during lamp ignition. Use Value: 3.5 V/ns dV/dt rating prevents spurious turn-on during rapid voltage transitions across lamp impedance.

Offline AC-DC Power Supplies

DC-DC Boost Converters

Use Scenario: Primary-side switch in 50–150 W universal-input flyback converters.

IC Role / Device Role / Timing Role: High-voltage switching element controlling energy transfer across transformer; operates at 65–132 kHz with zero-voltage switching assist.

Use Value: 500 V rating accommodates 385 V DC link with margin; 0.85 Ω R_DS(on) limits conduction loss to <1.2 W at full load.

Use Scenario: Main switch in isolated DC-DC boost stages for industrial battery charging (24 V → 400 V).

IC Role / Device Role / Timing Role: High-side power switch synchronizing with controller PWM; handles 8 A pulsed drain current.

Use Value: Repetitive avalanche capability absorbs inductive kickback during fault events without failure.

Motor Drive Half-Bridges

Lighting Ballast Circuits

Use Scenario: Low-side switch in 3-phase BLDC inverter stages for HVAC blowers (≤1 kW).

IC Role / Device Role / Timing Role: Fast-turning N-channel switch paired with complementary high-side driver; manages 5.1 A continuous phase current.

Use Value: 63 nC Q_g enables efficient gate driving with integrated half-bridge ICs (e.g., IR2104).

Use Scenario: Resonant switch in electronic CFL/LED ballasts operating at 25–50 kHz.

IC Role / Device Role / Timing Role: Hard-switched resonant transistor managing high dv/dt transitions during lamp ignition.

Use Value: 3.5 V/ns dV/dt rating prevents spurious turn-on during rapid voltage transitions across lamp impedance.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
STP8NK50ZFP	Zener-protected superjunction MOSFET; lower R_DS(on) (0.58 Ω), higher Q_g (72 nC), same 500 V rating.	Better conduction efficiency but slower switching; requires stronger gate drive.	Prefer for lower-loss, lower-frequency (<60 kHz) applications where thermal headroom is limited.
FQP5N50CTU	Planar MOSFET in TO-220; identical 500 V/8 A rating, slightly higher R_DS(on) (0.95 Ω), lower Q_g (45 nC).	Through-hole mounting; better heat sinking but larger footprint and higher parasitic inductance.	Prefer when board space allows and mechanical robustness or manual rework is prioritized over surface-mount density.

Compared with STP8NK50ZFP and FQP5N50CTU, the IRF840S offers optimal balance of avalanche ruggedness, surface-mount thermal performance, and gate drive simplicity - making it preferred for medium-power, high-reliability D2PAK-based designs where layout compactness and transient immunity are critical.

Availability

IRF840S is available at Aetrix Electronics and suitable for offline AC-DC power supplies, motor drive inverters, and lighting ballast circuits requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for IRF840S 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

Vishay Siliconix is a global leader in discrete semiconductors, specializing in high-reliability power MOSFETs, diodes, and optoelectronics for industrial, automotive, and computing markets.

The IRF840S belongs to Vishay's third-generation power MOSFET family engineered for rugged high-voltage switching in cost-sensitive, thermally constrained applications - emphasizing avalanche tolerance, surface-mount thermal efficiency, and ease of paralleling.

FAQ

What is the maximum continuous drain current for IRF840S at 100 °C case temperature?

The IRF840S supports 5.1 A continuous drain current at T_C = 100 °C, as specified in its Absolute Maximum Ratings table. This value reflects linear derating from 8.0 A at 25 °C using a 1.0 W/°C slope. Designers must verify PCB copper area and ambient airflow to sustain this current without exceeding 150 °C junction temperature. The IRF840S datasheet confirms this rating applies under steady-state thermal equilibrium with proper D2PAK pad layout.

Does IRF840S support logic-level gate drive?

No, the IRF840S is not a logic-level MOSFET. Its gate threshold voltage (V_GS(th)) ranges from 2.0 V to 4.0 V, but it requires 10 V gate-source voltage to achieve its specified R_DS(on) of 0.85 Ω. Driving IRF840S with only 5 V results in significantly higher on-resistance (>2 Ω) and excessive conduction loss. The IRF840S must be paired with a dedicated gate driver or level-shifting circuit capable of delivering ≥10 V to ensure full enhancement.

What is the avalanche energy rating of IRF840S, and how is it tested?

The IRF840S is rated for 510 mJ single-pulse avalanche energy (E_AS) and 13 mJ repetitive avalanche energy (E_AR). E_AS is measured under standardized unclamped inductive switching (UIS) conditions: V_DD = 50 V, I_AS = 8.0 A, T_J = 25 °C, with pulse width limited by junction temperature rise. The IRF840S datasheet specifies test circuit details in Figure 12a and defines repetitive rating limits in Note "a" - confirming suitability for moderate-energy inductive loads without external clamping.

Can IRF840S be paralleled with other units for higher current handling?

Yes, the IRF840S is explicitly designed for ease of paralleling, as noted in its Features section. Its positive temperature coefficient of R_DS(on) (confirmed in Fig. 4) ensures current sharing stability across multiple devices. To parallel IRF840S units, use matched gate resistors (R_g), symmetrical PCB layout with equal trace lengths, and shared thermal mass. The IRF840S datasheet validates this capability through characterization of dynamic parameters and thermal response under multi-device configurations.

What is the body diode reverse recovery time (t_rr) of IRF840S, and why does it matter?

The IRF840S body diode exhibits t_rr = 460–970 ns (typ./max) at T_J = 25 °C, I_F = 8.0 A, and dI/dt = 100 A/μs. This parameter directly impacts switching losses and voltage overshoot in hard-commutated topologies like synchronous rectifiers or half-bridges. A longer t_rr increases cross-conduction risk and EMI; designers must set adequate dead time - typically ≥1.5× t_rr - to prevent shoot-through. The IRF840S datasheet provides t_rr and Q_rr (4.2–8.9 μC) to enable precise timing analysis.

IRF840S Specifications

Product attributes: Attribute value

Manufacturer:: Vishay Siliconix

Series:: -

Package/Case:: TO-263-3, D2PAK (2 Leads + Tab), TO-263AB

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:: 8A (Tc)

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

Rds On (Max) @ Id, Vgs:: 850mOhm @ 4.8A, 10V

Vgs(th) (Max) @ Id:: 4V @ 250µA

Gate Charge (Qg) (Max) @ Vgs:: 63 nC @ 10 V

Vgs (Max):: ±20V

Input Capacitance (Ciss) (Max) @ Vds:: 1300 pF @ 25 V

FET Feature:: -

Power Dissipation (Max):: 3.1W (Ta), 125W (Tc)

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: TO-263 (D2PAK)

IRF840S FAQ

1.How can I place an order for IRF840S through Aetrix?

Please submit a Request for Quotation (RFQ) for IRF840S 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 IRF840S reliable?

The price and inventory of IRF840S are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for IRF840S is usually 5 days.

3.What payment methods are accepted for IRF840S?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for IRF840S transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for IRF840S?

IRF840S orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your IRF840S 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 IRF840S?

For technical support, including IRF840S datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your IRF840S requirements.

6.How does Aetrix verify that IRF840S is sourced from the original manufacturer or authorized distributors?

All IRF840S 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 IRF840S meets industry standards.

7.What is the process for return or replacement of IRF840S?

All IRF840S units undergo pre-shipment inspection (PSI). If there is an issue with IRF840S, 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 IRF840S part is unused and in its original packaging.

Return procedure for IRF840S:

1.Submit a request within 90 days.

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

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