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Home > Products > Discrete Semiconductor Products > Diodes > Rectifiers > Single Diodes

Taiwan Semiconductor Corporation SRAS840

Name: SRAS840
Brand: Taiwan Semiconductor Corporation
SKU: SRAS840
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SRAS840

Manufacturer:: Taiwan Semiconductor Corporation

Category:: Single Diodes

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

Datasheet:: SRAS840.pdf

Description:: 8A, 40V, SCHOTTKY RECTIFIER

Quantity:: RFQ Add To RFQ list

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Inventory:9,054

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Product details

Overview

SRAS840 from Taiwan Semiconductor is a single-die Schottky barrier rectifier in TO-263AB (D2PAK) package, rated for 8 A average forward current, 40 V repetitive peak reverse voltage (V_RRM), and 150 A non-repetitive surge current (I_FSM). It delivers low forward voltage drop (0.55 V at 8 A, 25°C) and operates up to 125°C junction temperature, targeting high-efficiency DC/DC converters and AC/DC adapters.

For engineers reviewing the SRAS840 datasheet, SRAS840 pinout, SRAS840 application, or SRAS840 equivalent, key selection criteria include its 40 V V_RRM, 0.55 V V_F at full load, 3 °C/W R_θJC, J-STD-020 Level 1 moisture sensitivity, and TO-263AB thermal performance in compact power stages.

Technical Context

The SRAS840 uses a planar Schottky junction structure with guard ring overvoltage protection, enabling stable operation under transient voltage stress. Its 40 V V_RRM and 0.55 V forward voltage at 8 A support high-frequency switching topologies with minimal conduction loss.

Thermally, it features a low 3 °C/W junction-to-case resistance and is qualified for 125°C maximum junction temperature. The device meets JESD201 Class 2 whisker resistance and RoHS/halogen-free compliance per IEC 61249-2-21.

Key Specifications

Parameter	Value and Actual Design Meaning
V_RRM	40 V - Maximum reverse blocking capability without breakdown in SMPS flyback or buck output stages
I_F	8 A - Continuous forward current rating defining usable output power in 12–24 V DC/DC designs
V_F @ 8 A, 25°C	0.55 V - Low conduction loss enabling >92% efficiency in 5–12 V output rails
I_FSM	150 A - Withstands inrush and short-circuit surges in adapter primary-side rectification
R_θJC	3 °C/W - Enables direct heatsinking to PCB copper or external metal slug for thermal management
T_J max	125 °C - Specifies safe operating limit for continuous conduction mode in enclosed industrial adapters
Mechanical Package	TO-263AB (D2PAK) - Surface-mount outline with exposed cathode tab for thermal and electrical integration

Pinout & Package

Package: TO-263AB (D2PAK), 3-terminal surface-mount package with exposed cathode pad. Cathode marked by polarity symbol on top surface; anode and cathode terminals electrically isolated except through die.

Pin/Terminal	Circuit Role	Design Meaning
Anode (Lead 1)	Input current entry point	Soldered to input rail or transformer secondary; carries full forward current into die
Cathode (Exposed Pad)	Output current exit & thermal path	Primary heat dissipation surface; must be connected to large copper pour or heatsink
Tab / Cathode (Lead 2)	Secondary cathode connection	Provides redundant low-inductance return path; electrically tied to exposed pad

Key Features

Feature	Design Value
Guard ring overvoltage protection	Prevents premature edge breakdown during line transients in offline SMPS inputs
Low 0.55 V forward voltage	Reduces power loss by ~0.4 W vs. comparable 0.75 V diodes at 8 A, improving thermal margin
J-STD-020 Level 1 moisture sensitivity	Enables standard SMT reflow without baking or dry-pack handling
150 A I_FSM surge rating	Supports robust start-up in high-capacitance output stages without derating
Halogen-free & RoHS compliant	Meets IPC-J-STD-609 and EU Directive 2011/65/EU for green manufacturing

Applications

AC/DC Adapter Secondary Rectification	Isolated DC/DC Converter Output Stage
Use Scenario: 12 V/5 A output rectification in universal-input wall adapters with active clamp flyback topology. IC Role / Device Role / Timing Role: Uncontrolled power rectifier converting transformer secondary AC to regulated DC output. Use Value: 0.55 V V_F minimizes conduction loss at full load, enabling compact thermal design without forced air cooling.	Use Scenario: 5 V/6 A output rectification in telecom DC/DC modules with synchronous rectifier control disabled. IC Role / Device Role / Timing Role: Freewheeling diode providing current path during high-side switch off-time. Use Value: 150 A I_FSM withstands output capacitor inrush and short-circuit events without failure.
Industrial Power Supply Input Protection	LED Driver Constant-Current Stage
Use Scenario: Reverse-polarity and back-EMF protection in 24 V input industrial PLC power inputs. IC Role / Device Role / Timing Role: Polarity guard diode placed before bulk capacitance and regulator IC. Use Value: Guard ring structure ensures reliable 40 V reverse hold-off during 100 V transients per IEC 61000-4-4.	Use Scenario: Output rectification in constant-current LED drivers powering 10–20 strings of high-brightness LEDs. IC Role / Device Role / Timing Role: Main current path delivering steady DC to LED load under PWM dimming. Use Value: 125°C T_J max supports operation in sealed, thermally constrained LED housings.

AC/DC Adapter Secondary Rectification

Isolated DC/DC Converter Output Stage

Use Scenario: 12 V/5 A output rectification in universal-input wall adapters with active clamp flyback topology.

IC Role / Device Role / Timing Role: Uncontrolled power rectifier converting transformer secondary AC to regulated DC output.

Use Value: 0.55 V V_F minimizes conduction loss at full load, enabling compact thermal design without forced air cooling.

Use Scenario: 5 V/6 A output rectification in telecom DC/DC modules with synchronous rectifier control disabled.

IC Role / Device Role / Timing Role: Freewheeling diode providing current path during high-side switch off-time.

Use Value: 150 A I_FSM withstands output capacitor inrush and short-circuit events without failure.

Industrial Power Supply Input Protection

LED Driver Constant-Current Stage

Use Scenario: Reverse-polarity and back-EMF protection in 24 V input industrial PLC power inputs.

IC Role / Device Role / Timing Role: Polarity guard diode placed before bulk capacitance and regulator IC.

Use Value: Guard ring structure ensures reliable 40 V reverse hold-off during 100 V transients per IEC 61000-4-4.

Use Scenario: Output rectification in constant-current LED drivers powering 10–20 strings of high-brightness LEDs.

IC Role / Device Role / Timing Role: Main current path delivering steady DC to LED load under PWM dimming.

Use Value: 125°C T_J max supports operation in sealed, thermally constrained LED housings.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Schottky rectifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
Vishay VS-8EWH04FN-M3	Same 40 V V_RRM, 8 A I_F, but TO-252AA (DPAK); V_F = 0.54 V @ 8 A; R_θJC = 4.5 °C/W	Lower thermal performance limits power density in high-ambient environments	Preferred where board space is constrained but thermal budget allows DPAK footprint
ON Semiconductor SB840	Same 40 V V_RRM, 8 A I_F, TO-263AB; V_F = 0.57 V @ 8 A; T_J max = 150°C	Higher junction temperature rating enables extended operation in sealed enclosures	Chosen when >125°C ambient operation is required and 0.02 V higher V_F is acceptable

Compared with VS-8EWH04FN-M3 and SB840, the SRAS840 offers optimal balance of low V_F, proven TO-263AB thermal interface, and J-STD-020 Level 1 process compatibility-making it ideal for high-volume, thermally demanding adapter production.

Availability

SRAS840 is available at Aetrix Electronics and suitable for AC/DC adapters, isolated DC/DC converters, and industrial power supply input protection requiring stable component supply, consistent parametric binning, and long-term manufacturability.

Supply support for SRAS840 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in power rectifiers, TVS devices, and MOSFETs.

The SRAS8xx series was designed specifically for high-efficiency, high-reliability secondary-side rectification in cost-sensitive consumer and industrial power supplies, emphasizing low V_F, robust surge immunity, and automated assembly compatibility.

FAQ

What is the maximum junction temperature rating for the SRAS840?

The SRAS840 has a maximum junction temperature (T_J) rating of 125°C, as specified in the Absolute Maximum Ratings table. This value applies under continuous conduction conditions and defines the upper thermal limit for reliable long-term operation in applications such as AC/DC adapters and DC/DC converters where ambient temperatures may reach 70–85°C.

Does the SRAS840 have a guard ring structure, and what benefit does it provide?

Yes, the SRAS840 incorporates a guard ring structure explicitly cited in its features list. This design mitigates edge breakdown under high dv/dt or transient overvoltage conditions-such as those encountered during ESD events or line surges in SMPS inputs-thereby improving reliability without requiring external snubbers in many 40 V-class applications.

What is the forward voltage drop of the SRAS840 at rated current and room temperature?

The SRAS840 exhibits a maximum forward voltage (V_F) of 0.55 V at 8 A forward current and 25°C junction temperature, as confirmed in the Electrical Specifications table. This value is measured under pulsed conditions (PW = 0.3 ms) and represents the typical conduction loss used for efficiency calculations in 12–24 V output power stages.

Is the SRAS840 compatible with lead-free reflow soldering processes?

Yes, the SRAS840 is qualified for lead-free reflow soldering. Its matte tin-plated leads meet J-STD-002 solderability requirements, and its moisture sensitivity level is rated J-STD-020 Level 1-meaning it can be subjected to standard Pb-free reflow profiles (peak 260°C) without baking or special handling.

What packaging format is used for the SRAS840, and how many units are included per reel?

The SRAS840 is supplied in TO-263AB (D2PAK) package on tape-and-reel format, with 800 units per reel, as stated in the Ordering Information section. This packaging supports high-speed automated placement and is compatible with standard pick-and-place equipment used in high-volume power supply manufacturing.

SRAS840 Specifications

Product attributes: Attribute value

Manufacturer:: Taiwan Semiconductor Corporation

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

Technology:: Schottky

Voltage - DC Reverse (Vr) (Max):: 40 V

Current - Average Rectified (Io):: 8A

Voltage - Forward (Vf) (Max) @ If:: 550 mV @ 8 A

Speed:: Fast Recovery =< 500ns, > 200mA (Io)

Reverse Recovery Time (trr):: -

Current - Reverse Leakage @ Vr:: 100 µA @ 40 V

Capacitance @ Vr, F:: -

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: TO-263AB (D2PAK)

Operating Temperature - Junction:: -55°C ~ 125°C

SRAS840 FAQ

1.How can I place an order for SRAS840 through Aetrix?

Please submit a Request for Quotation (RFQ) for SRAS840 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 SRAS840 reliable?

The price and inventory of SRAS840 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SRAS840 is usually 5 days.

3.What payment methods are accepted for SRAS840?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SRAS840 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SRAS840?

SRAS840 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SRAS840 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 SRAS840?

For technical support, including SRAS840 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SRAS840 requirements.

6.How does Aetrix verify that SRAS840 is sourced from the original manufacturer or authorized distributors?

All SRAS840 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 SRAS840 meets industry standards.

7.What is the process for return or replacement of SRAS840?

All SRAS840 units undergo pre-shipment inspection (PSI). If there is an issue with SRAS840, 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 SRAS840 part is unused and in its original packaging.

Return procedure for SRAS840:

1.Submit a request within 90 days.

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

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