Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

Vishay Siliconix IRF840AS

Name: IRF840AS
Brand: Vishay Siliconix
SKU: IRF840AS
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: IRF840AS

Manufacturer:: Vishay Siliconix

Category:: FETs, MOSFETs

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

Datasheet:: IRF840AS.pdf

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

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:9,519

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

IRF840AS from Vishay Siliconix is a 500 V, 8.0 A N-channel power MOSFET in D2PAK (TO-263) package, optimized for high-voltage switching in SMPS and UPS systems. It delivers R_DS(on) = 0.85 Ω at V_GS = 10 V, Q_g = 38 nC, and 510 mJ single-pulse avalanche energy - enabling robust, efficient hard-switching in forward and bridge topologies.

For engineers reviewing the IRF840AS datasheet, IRF840AS pinout, IRF840AS application, or IRF840AS equivalent, key selection criteria include its 500 V V_DS, 125 W P_D at T_C = 25 °C, 1.0 °C/W R_thJC, body diode t_rr = 422–633 ns, and dV/dt ruggedness of 5.0 V/ns - all critical for reliable operation in high-dV/dt, inductive-load environments.

Technical Context

The IRF840AS employs planar vertical DMOS technology with fully characterized avalanche capability and effective output capacitance (C_{oss eff.} = 56 pF). Its gate threshold voltage (V_GS(th) = 2.0–4.0 V) and low Q_gd/Q_g ratio (18/38 nC) support stable turn-on under varying drive conditions and reduce Miller-induced shoot-through risk.

Thermally, it features a low junction-to-case thermal resistance (R_thJC ≤ 1.0 °C/W) and is rated for T_J = –55 to +150 °C. The device is specified for repetitive avalanche (I_AR = 8.0 A, E_AR = 13 mJ) and validated for unclamped inductive switching per JEDEC JESD24-11, supporting rugged design in flyback and resonant converters.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	500 V - supports primary-side switching in offline 400 V DC bus and universal AC-input SMPS
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	38 nC - determines gate driver current requirement (~3.8 mA avg. for 100 kHz f_sw)
E_AS	510 mJ - allows safe energy absorption during unclamped inductive turn-off without external snubber
t_rr	422–633 ns - defines reverse recovery window impacting switching loss and EMI in hard-switched topologies
R_thJC	≤ 1.0 °C/W - permits high-power dissipation with minimal thermal interface resistance to heatsink
dV/dt rating	5.0 V/ns - ensures immunity to false turn-on during fast voltage transients across drain-source

Pinout & Package

D2PAK (TO-263) surface-mount package with exposed drain pad for thermal and electrical connection; 3-pin configuration (G, D, S), standard lead pitch 2.54 mm, footprint per Vishay AN826 recommended pads.

Pin/Terminal	Circuit Role	Design Meaning
G (Gate)	Control terminal	Receives 10 V logic-level drive; requires <38 nC charge for full enhancement; low C_iss = 1018 pF reduces drive burden
D (Drain)	High-side power switch node	Connected to exposed thermal pad; carries full load current and withstands 500 V transient spikes; electrically tied to heatsink
S (Source)	Reference node / return path	Common source for gate drive loop; body diode anode; must be routed with low inductance to minimize ringing during switching

Key Features

Feature	Design Value
Low gate charge (Q_g = 38 nC)	Reduces gate driver power consumption and simplifies drive circuit design for 50–500 kHz SMPS
Enhanced avalanche ruggedness	Validated 510 mJ single-pulse and 13 mJ repetitive avalanche energy enables snubberless operation in inductive loads
Characterized C_{oss eff.} = 56 pF	Enables accurate soft-switching timing prediction and ZVS/ZCS design in resonant converters
5.0 V/ns dV/dt immunity	Prevents spurious turn-on during high-slew-rate transitions in half/full-bridge configurations
Body diode t_rr = 422–633 ns	Supports synchronous rectification evaluation and limits reverse recovery loss in freewheeling paths

Applications

Switch Mode Power Supply (SMPS)	Uninterruptible Power Supply (UPS)
Use Scenario: Primary-side switch in 2-transistor forward converter operating from 375 V DC bus with 100 kHz switching frequency. IC Role / Device Role / Timing Role: High-voltage N-channel power switch handling 8 A peak drain current and absorbing 510 mJ avalanche energy during turn-off. Use Value: Eliminates need for external clamping circuits due to guaranteed single-pulse avalanche rating and low R_DS(on).	Use Scenario: Inverter-stage switching device in line-interactive UPS delivering 1 kVA output with battery backup. IC Role / Device Role / Timing Role: Half-bridge leg switch managing bidirectional power flow and sustaining 500 V DC link voltage under surge conditions. Use Value: 5.0 V/ns dV/dt rating prevents false triggering during rapid bus voltage transitions during transfer events.
High-Speed Power Switching	Industrial Motor Drive Stage
Use Scenario: Solid-state relay replacement in programmable logic controller (PLC) output module switching 240 V AC resistive loads. IC Role / Device Role / Timing Role: Fast-turning, avalanche-rated switch replacing electromechanical relays for >1 million cycle life. Use Value: 32 A pulsed drain current (I_DM) and 8.0 A continuous rating enable direct control of 10 A loads without derating.	Use Scenario: Brake chopper switch in 48 V DC-fed servo drive dissipating regenerative energy into braking resistor. IC Role / Device Role / Timing Role: Energy-dumping switch activated during deceleration, subjected to repetitive inductive kickback. Use Value: Repetitive avalanche rating (I_AR = 8.0 A, E_AR = 13 mJ) ensures long-term reliability without snubber degradation.

Switch Mode Power Supply (SMPS)

Uninterruptible Power Supply (UPS)

Use Scenario: Primary-side switch in 2-transistor forward converter operating from 375 V DC bus with 100 kHz switching frequency.

IC Role / Device Role / Timing Role: High-voltage N-channel power switch handling 8 A peak drain current and absorbing 510 mJ avalanche energy during turn-off.

Use Value: Eliminates need for external clamping circuits due to guaranteed single-pulse avalanche rating and low R_DS(on).

Use Scenario: Inverter-stage switching device in line-interactive UPS delivering 1 kVA output with battery backup.

IC Role / Device Role / Timing Role: Half-bridge leg switch managing bidirectional power flow and sustaining 500 V DC link voltage under surge conditions.

Use Value: 5.0 V/ns dV/dt rating prevents false triggering during rapid bus voltage transitions during transfer events.

High-Speed Power Switching

Industrial Motor Drive Stage

Use Scenario: Solid-state relay replacement in programmable logic controller (PLC) output module switching 240 V AC resistive loads.

IC Role / Device Role / Timing Role: Fast-turning, avalanche-rated switch replacing electromechanical relays for >1 million cycle life.

Use Value: 32 A pulsed drain current (I_DM) and 8.0 A continuous rating enable direct control of 10 A loads without derating.

Use Scenario: Brake chopper switch in 48 V DC-fed servo drive dissipating regenerative energy into braking resistor.

IC Role / Device Role / Timing Role: Energy-dumping switch activated during deceleration, subjected to repetitive inductive kickback.

Use Value: Repetitive avalanche rating (I_AR = 8.0 A, E_AR = 13 mJ) ensures long-term reliability without snubber degradation.

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
STP8NK50ZFP	Zener-protected superjunction MOSFET; V_DS = 500 V, R_DS(on) = 0.75 Ω, Q_g = 34 nC, but no specified avalanche energy rating	Lacks documented E_AS; unsuitable where unclamped inductive switching is routine	Prefer IRF840AS when avalanche robustness is required; STP8NK50ZFP offers lower R_DS(on) where snubbers are used
IXTH8N50L	Lateral N-channel MOSFET; V_DS = 500 V, R_DS(on) = 0.95 Ω, Q_g = 28 nC, avalanche rated to 320 mJ only	Lower E_AS and higher R_DS(on); limited to lower-energy switching nodes	Select IRF840AS for higher-energy fault tolerance; IXTH8N50L fits space-constrained layouts needing lower Q_g

Compared with STP8NK50ZFP and IXTH8N50L, the IRF840AS provides the highest verified single-pulse avalanche energy (510 mJ) and lowest thermal resistance (1.0 °C/W), making it optimal for thermally demanding, high-reliability SMPS and UPS inverters where layout constraints permit D2PAK mounting.

Availability

IRF840AS is available at Aetrix Electronics and suitable for switch mode power supplies, uninterruptible power supplies, and industrial motor drive stages requiring stable component supply, long-lifecycle availability, and traceable sourcing.

Supply support for IRF840AS 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 applications.

The IRF840AS belongs to Vishay's high-voltage planar MOSFET product line, engineered for ruggedness in hard-switched power conversion - emphasizing avalanche capability, dV/dt immunity, and thermal performance in TO-263 packaging.

FAQ

What is the maximum continuous drain current rating for the IRF840AS at 100 °C case temperature?

The IRF840AS has a continuous drain current (I_D) rating of 5.1 A at T_C = 100 °C, derated linearly from 8.0 A at 25 °C using a 1.0 W/°C derating factor. This value is confirmed in the Absolute Maximum Ratings table of Vishay document 91066 and reflects thermal limits under PCB-mount conditions with adequate heatsinking.

Does the IRF840AS have a specified body diode reverse recovery time (t_rr)?

Yes, the IRF840AS specifies t_rr = 422–633 ns at T_J = 25 °C, I_F = 8.0 A, and dI/dt = 100 A/μs. This parameter is measured per JEDEC standards and appears in the "Drain-Source Body Diode Characteristics" section of the datasheet (document 91066, page 2).

Is the IRF840AS RoHS-compliant and halogen-free?

Yes, the IRF840AS is offered in both lead (Pb)-free and halogen-free versions (e.g., IRF840ASTRRPbF). Vishay confirms RoHS compliance per EU Directive 2011/65/EU and halogen-free status per IEC 61249-2-21, with material categorization defined in document 99912.

What is the gate threshold voltage range for the IRF840AS?

The IRF840AS has a gate threshold voltage (V_GS(th)) range of 2.0 V to 4.0 V at V_DS = V_GS and I_D = 250 μA. This is specified in the "Static" section of the Electrical Characteristics table (document 91066, page 2) and ensures compatibility with standard 5 V and 10 V logic-level gate drivers.

Can the IRF840AS be used in a full-bridge topology without external snubbers?

Yes - the IRF840AS supports snubberless operation in full-bridge topologies due to its validated 510 mJ single-pulse avalanche energy (E_AS) and 5.0 V/ns dV/dt immunity. These characteristics allow safe turn-off under inductive load conditions typical in bridge configurations, provided layout minimizes stray inductance and thermal management meets R_thJC ≤ 1.0 °C/W requirements.

IRF840AS 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:: 38 nC @ 10 V

Vgs (Max):: ±30V

Input Capacitance (Ciss) (Max) @ Vds:: 1018 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)

IRF840AS FAQ

1.How can I place an order for IRF840AS through Aetrix?

Please submit a Request for Quotation (RFQ) for IRF840AS 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 IRF840AS reliable?

The price and inventory of IRF840AS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for IRF840AS is usually 5 days.

3.What payment methods are accepted for IRF840AS?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for IRF840AS transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for IRF840AS?

IRF840AS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your IRF840AS 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 IRF840AS?

For technical support, including IRF840AS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your IRF840AS requirements.

6.How does Aetrix verify that IRF840AS is sourced from the original manufacturer or authorized distributors?

All IRF840AS 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 IRF840AS meets industry standards.

7.What is the process for return or replacement of IRF840AS?

All IRF840AS units undergo pre-shipment inspection (PSI). If there is an issue with IRF840AS, 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 IRF840AS part is unused and in its original packaging.

Return procedure for IRF840AS:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-11 Comparator Circuit: Voltage Thresholds, Op-Amp Differences, LM393 and Practical Design

Comparator circuit design covering voltage thresholds, input limits, open-collector outputs, LM393 wiring, op-amp differences, hysteresis, timing, window detection and practical fault diagnosis.

2026-09-10 Schmitt Trigger Explained: Hysteresis, Circuits, Inverters and Applications

Schmitt triggers use separate rising and falling thresholds to stabilize slow or noisy signals. This guide covers hysteresis, 74HC14 and 74HCT14 selection, comparator calculations, RC oscillators and p…

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …