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Diodes Incorporated ALS8W40A
- Part No.:
- ALS8W40A
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-218AB
- Datasheet:
-
ALS8W40A.pdf
- Description:
- Transient Voltage Suppressor PP
- Quantity:
- Payment:
- Shipping:
Inventory:5,476
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Product details
Overview
ALS8W40A from Diodes Incorporated is a unidirectional surface-mount load dump transient voltage suppressor in DO-218 package, rated for 40 V stand-off voltage (VWM), 44.4–49.1 V breakdown (VBR), 6600 W peak pulse power (10/1000 µs), 102 A peak pulse current, and 64.5 V clamping voltage (VC) - designed for automotive ECU-level load dump protection per ISO7637-2 and ISO16750-2.
For engineers reviewing the ALS8W40A datasheet, ALS8W40A pinout, ALS8W40A application, or ALS8W40A equivalent, this device serves as a high-energy, high-temperature-stable clamping diode with low thermal resistance, automotive-grade qualification, and lead-free/Green compliance - critical for robust 12 V/24 V vehicle subsystems requiring precise overvoltage suppression during alternator load dump events.
Technical Context
The ALS8W40A operates as a unidirectional TVS diode optimized for exponential surge waveforms up to 10 ms, delivering 5200 W at 10/10000 µs while maintaining stable clamping performance across –55°C to +175°C junction temperature. Its DO-218 package features heatsink-anode polarity and low RθJC, enabling efficient thermal dissipation during repetitive transients.
It meets ISO7637-2 Level V (load dump) and ISO16750-2 test conditions without derating below +125°C case temperature, with maximum forward voltage of 1.8 V at 100 A (8.3 ms half-sine) and reverse leakage ≤10 µA at VWM (TJ = 25°C) and ≤150 µA at TJ = +175°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 40 V - Maximum continuous reverse operating voltage before conduction begins; defines system nominal bus voltage compatibility (e.g., 24 V automotive). |
| VBR (min/max) | 44.4 V / 49.1 V - Breakdown voltage range at 5 mA test current; ensures reliable turn-on margin above VWM under production variation. |
| VC @ IPPM | 64.5 V - Clamping voltage at 102 A peak pulse (10/1000 µs); limits downstream IC stress during worst-case load dump. |
| PPPM (10/1000 µs) | 6600 W - Peak pulse power handling; supports high-energy transients typical of 24 V commercial vehicle alternator dumps. |
| IFSM | 700 A - Non-repetitive forward surge rating (8.3 ms half-sine); validates robustness against inrush and short-circuit faults. |
| TJ Range | –55°C to +175°C - Extended junction temperature capability; enables placement near hot ECU components without derating. |
Pinout & Package
Package: DO-218 - Surface-mount plastic package with integral heatsink tab (anode), matte tin-plated terminals, UL 94V-0 molding compound, and moisture sensitivity level 1. Polarity: Heatsink is anode; cathode marked by bar on body.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Heatsink Tab) | Power input / GND return path | Primary thermal and electrical connection point; must be soldered to large copper pour for effective heat transfer and low-inductance grounding. |
| Cathode (Lead) | Transient voltage clamp output | Connected to protected line (e.g., battery rail); conducts surge current to anode when VIN exceeds VBR. |
Key Features
| Feature | Design Value |
|---|---|
| High-temperature stability | Leakage remains ≤150 µA at +175°C junction - ensures consistent clamping behavior in under-hood ECU environments. |
| Low thermal resistance | RθJC optimized via DO-218 heatsink tab - enables >5 kW dissipation without external heatsink at TC ≤ +125°C. |
| Automotive qualification | AEC-Q101 qualified, PPAP-capable, manufactured in IATF 16949 facilities - fulfills OEM supply chain traceability and reliability requirements. |
| Green compliance | Halogen- and antimony-free (<900 ppm Br/Cl, <1000 ppm Sb), RoHS 3 compliant - satisfies global environmental regulations for Tier 1 automotive sourcing. |
Applications
| Engine Control Unit (ECU) Protection | Body Control Module (BCM) Power Rail |
|---|---|
Use Scenario: Protects microcontroller power inputs during alternator load dump events in gasoline/diesel engine ECUs. IC Role / Device Role / Timing Role: Unidirectional clamping diode placed between battery rail and DC-DC converter input. Use Value: Limits transient voltage to ≤64.5 V, preventing latch-up or damage to 5 V/3.3 V LDOs and MCU I/Os rated for 40 V absolute max. | Use Scenario: Shields BCM power distribution network from load dump surges induced by headlight or HVAC relay switching. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 12 V main input before fuse box and local regulators. Use Value: Absorbs 6600 W pulses without degradation, maintaining system uptime and eliminating need for redundant TVS stages. |
| Commercial Vehicle Telematics Unit | Electric Power Steering (EPS) Module |
Use Scenario: Safeguards LTE/CAN gateway electronics in fleet telematics units exposed to 24 V truck/bus battery systems. IC Role / Device Role / Timing Role: Front-end transient suppressor on OBD-II or direct battery interface. Use Value: Withstands 10/10000 µs surges up to 5200 W - matching extended-duration load dump profiles in heavy-duty vehicles. | Use Scenario: Protects motor driver gate drivers and position sensor supplies in EPS modules subject to frequent load switching. IC Role / Device Role / Timing Role: Localized clamping device adjacent to H-bridge power stage input. Use Value: Low 1.8 V forward drop at 100 A minimizes conduction loss during fault recovery, preserving driver bias integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar load dump protection applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ40A | Lower PPPM (400 W), SMA package, VC = 64.5 V at 32.4 A - 3× lower surge capacity. | Rated for passenger car infotainment only; insufficient for commercial vehicle or ECU front-end use. | Select only for cost-sensitive, low-energy 12 V subcircuits where full load dump immunity is not required. |
| SMCJ40A | PPPM = 1500 W, SMC package, VC = 64.5 V at 75.8 A - 4.4× lower energy handling than ALS8W40A. | Suitable for secondary protection or non-critical modules; cannot replace ALS8W40A in primary battery rail positions. | Use as backup clamp or in space-constrained designs where DO-218 footprint is impractical, but verify system-level surge margin. |
Compared with SMAJ40A and SMCJ40A, the ALS8W40A delivers 4.4× and 1.6× higher peak pulse power respectively, with superior thermal management via its heatsink-anode DO-218 package - making it the only option qualified for primary load dump suppression in AEC-Q101-compliant 24 V automotive control modules.
Availability
ALS8W40A is available at Aetrix Electronics and suitable for automotive ECU protection, body control module power rails, and commercial vehicle telematics units requiring stable component supply, long-lifecycle support, and AEC-Q101-compliant surge suppression.
Supply support for ALS8W40A 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability components for automotive, industrial, and computing markets with IATF 16949-certified manufacturing.
The ALS8WxxA series is part of Diodes' automotive-grade TVS portfolio, engineered specifically for ISO7637-2/ISO16750-2 load dump compliance in engine control, chassis, and safety-critical electronic modules.
FAQ
What is the maximum clamping voltage of ALS8W40A under full-rated surge current?
The ALS8W40A exhibits a maximum clamping voltage (VC) of 64.5 V when subjected to its rated peak pulse current of 102 A under the 10/1000 µs waveform. This value is guaranteed across production lots and validated per DS43856 Rev. 9 test conditions at TA = +25°C, with no derating required up to +125°C case temperature.
Is ALS8W40A qualified to AEC-Q101, and what does that entail for automotive use?
Yes, ALS8W40A is AEC-Q101 qualified. This means it has passed stress tests including HTGB, HTRB, TST, and surge endurance per JESD22 standards, with PPAP documentation support and production in IATF 16949-certified facilities - fulfilling Tier 1 OEM requirements for mission-critical automotive electronics such as engine control and EPS modules.
Can ALS8W40A be used in 12 V and 24 V systems interchangeably?
ALS8W40A is optimized for 24 V nominal systems (VWM = 40 V), but may be used in 12 V applications where higher clamping margin is acceptable. Its 44.4–49.1 V VBR range provides adequate margin above 12 V rail transients, though lower-VWM variants like ALS8W15A are preferred for tighter 12 V design constraints.
What is the recommended PCB layout for optimal thermal and electrical performance?
Mount the DO-218 anode tab directly to a ≥25 mm² internal or external copper pour with ≥4 thermal vias (0.3 mm diameter) connecting to inner ground planes. Keep cathode trace short and wide (≥1.5 mm), avoid sharp bends, and maintain ≥1.5 mm creepage/clearance to adjacent high-voltage nodes per IPC-2221B Class C.
ALS8W40A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- DO-218AB
- Series:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 40V
- Voltage - Breakdown (Min):
- 44.4V
- Voltage - Clamping (Max) @ Ipp:
- 64.5V
- Current - Peak Pulse (10/1000µs):
- 102A
- Power - Peak Pulse:
- 6600W (6.6kW)
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-218
ALS8W40A FAQ
1.How can I place an order for ALS8W40A through Aetrix?
Please submit a Request for Quotation (RFQ) for ALS8W40A 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 ALS8W40A reliable?
The price and inventory of ALS8W40A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ALS8W40A is usually 5 days.
3.What payment methods are accepted for ALS8W40A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ALS8W40A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ALS8W40A?
ALS8W40A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ALS8W40A 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 ALS8W40A?
For technical support, including ALS8W40A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ALS8W40A requirements.
6.How does Aetrix verify that ALS8W40A is sourced from the original manufacturer or authorized distributors?
All ALS8W40A 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 ALS8W40A meets industry standards.
7.What is the process for return or replacement of ALS8W40A?
All ALS8W40A units undergo pre-shipment inspection (PSI). If there is an issue with ALS8W40A, 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 ALS8W40A part is unused and in its original packaging.
Return procedure for ALS8W40A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ALS8W40A Tags
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