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Diodes Incorporated ALS5W18A
- Part No.:
- ALS5W18A
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-218AB
- Datasheet:
-
ALS5W18A.pdf
- Description:
- Transient Voltage Suppressor PP
- Quantity:
- Payment:
- Shipping:
Inventory:5,698
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Product details
Overview
ALS5W18A from Diodes Incorporated is a unidirectional surface-mount load dump transient voltage suppressor in DO-218 package, rated for 18 V stand-off voltage (VWM), 20.0–22.1 V breakdown (VBR), 3600 W peak pulse power (10/1000 µs), and 123 A peak pulse current - designed specifically for automotive ECU load dump protection.
For engineers reviewing the ALS5W18A datasheet, ALS5W18A pinout, ALS5W18A application, or ALS5W18A equivalent, key selection criteria include clamping voltage (29.2 V at IPPM), junction temperature range (−55 °C to +175 °C), AEC-Q101 qualification, ISO7637-2 compliance, and thermal resistance performance under high-current surge conditions.
Technical Context
This device operates as a unidirectional avalanche diode with anode-connected heatsink configuration, optimized for fast clamping of 12 V automotive system load dump transients (ISO7637-2 Pulse 5a). Its low thermal resistance enables sustained energy dissipation up to 2800 W under 10/10,000 µs waveform.
It features a maximum forward voltage of 2.0 V at 100 A (8.3 ms half-sine), reverse leakage ≤10 µA at VWM, and clamping voltage tightly specified at 29.2 V - ensuring predictable overvoltage protection for downstream DC-DC converters and microcontrollers in engine control units.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18.0 V - Maximum continuous reverse operating voltage before conduction begins; sets system working margin below clamp threshold. |
| VBR (min/max) | 20.0 V / 22.1 V at 5.0 mA - Confirmed avalanche onset range; ensures reliable triggering above nominal 12 V rail during surge events. |
| VC @ IPPM | 29.2 V - Clamping voltage at 123 A (10/1000 µs); limits stress on protected ICs to safe levels during load dump. |
| PPPM (10/1000 µs) | 3600 W - Peak surge power handling capacity; meets stringent automotive load dump requirements per ISO16750-2. |
| IFSM | 500 A - Non-repetitive forward surge rating (8.3 ms); supports robustness against repeated ignition coil switching surges. |
| TJ Range | −55 °C to +175 °C - Full automotive junction temperature operation; validated for under-hood ECU environments. |
Pinout & Package
ALS5W18A uses the DO-218 plastic package with heatsink-integrated anode terminal and cathode bar marking. The case serves as the anode connection, enabling low-inductance, high-current mounting directly to PCB copper pour or heatsink.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Heatsink) | Main current path input | Electrically connected to molded case; must be soldered to large copper area for thermal and electrical performance. |
| Cathode (Bar-marked lead) | Clamping output node | Connected to protected circuit rail; conducts surge current to ground when VWM exceeded. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive under-hood use including temperature cycling, humidity, and mechanical shock per JESD22 standards. |
| ISO7637-2 & ISO16750-2 compliant | Passes Pulse 5a (load dump) testing up to 40 V test level with 10 Ω source impedance and 500 ms duration. |
| Low clamping ratio (VC/VWM = 1.62) | Minimizes overvoltage margin required for protected ICs - reduces need for oversized input capacitors or derating. |
| MSL Level 1, 260 °C reflow compatible | Enables standard SMT assembly without moisture sensitivity concerns or pre-bake requirements. |
| Halogen- and antimony-free "Green" construction | Meets EU RoHS 3 (2015/863/EU) with Br+Cl <1500 ppm and Sb <1000 ppm - supports eco-compliant vehicle programs. |
Applications
| Engine Control Unit (ECU) Protection | Body Control Module (BCM) Power Input |
|---|---|
Use Scenario: Protecting 12 V supply rail of engine ECU against alternator load dump transients during battery disconnect. IC Role / Device Role / Timing Role: Unidirectional TVS diode clamping surge to ≤29.2 V within nanoseconds to prevent damage to MCU, CAN transceivers, and analog sensors. Use Value: Enables direct integration into compact ECU PCB layouts with no external series impedance, leveraging DO-218 thermal mass for repeatable 3600 W surge handling. | Use Scenario: Safeguarding BCM power entry against load dump and jump-start induced overvoltage in vehicle body electronics. IC Role / Device Role / Timing Role: Fast-acting clamping element placed upstream of DC-DC converter input, absorbing >95% of surge energy before it reaches regulation stage. Use Value: Eliminates need for additional filtering or derating of input capacitors due to tight 29.2 V clamping and −55 °C to +175 °C operational range. |
| LED Headlamp Driver Protection | Transmission Control Module (TCM) Interface |
Use Scenario: Shielding high-power LED driver ICs from inductive kickback and load dump in adaptive front lighting systems. IC Role / Device Role / Timing Role: Primary overvoltage suppression device on 12 V input rail, activated within 1 ns to limit transient amplitude seen by buck controller and gate drivers. Use Value: Maintains LED driver uptime during cold-crank and load dump events without latch-up or degradation, verified over 1000+ surge cycles. | Use Scenario: Securing LIN/CAN interface power rails in TCM against battery line disturbances during gear-shift solenoid actuation. IC Role / Device Role / Timing Role: Standoff-rated protector (18 V) that remains non-conductive during normal operation but clamps within 100 ns during 30 V+ transients. Use Value: Prevents false resets and communication errors in transmission logic by limiting rail excursion to 29.2 V - well below 33 V absolute max ratings of most interface ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar load dump protection applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A (ON Semiconductor) | DO-214AC package; lower PPPM (400 W), higher VC (29.2 V same, but at only 12.9 A), smaller thermal mass. | Not rated for ISO7637-2 Pulse 5a; suitable only for lower-energy transients or secondary protection. | Select ALS5W18A when full automotive load dump compliance and 3600 W capability are mandatory. |
| SMCJ18A (Littelfuse) | DO-214AB package; PPPM = 1500 W (10/1000 µs); VC = 29.2 V at 51.3 A; lacks AEC-Q101 certification. | Requires parallel devices or external heatsinking to match ALS5W18A's single-device 3600 W rating. | Choose ALS5W18A for space-constrained, single-component, AEC-Q101-compliant solutions in ECU-level designs. |
Compared with SMAJ18A and SMCJ18A, ALS5W18A delivers 2.4× and 2.4× higher peak pulse power respectively in a thermally superior DO-218 package, with certified AEC-Q101 reliability and full ISO7637-2 Pulse 5a validation - making it the only single-device solution meeting OEM Tier-1 ECU surge requirements without derating or redundancy.
Availability
ALS5W18A is available at Aetrix Electronics and suitable for automotive engine control units, body control modules, and LED headlamp driver systems requiring stable component supply across extended production lifecycles and rigorous environmental qualification.
Supply support for ALS5W18A 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.
The ALS5WxxA series is part of Diodes' Automotive Transient Voltage Suppressor portfolio, engineered specifically for ISO7637-2-compliant load dump protection in 12 V vehicle architectures - emphasizing thermal robustness, AEC-Q101 qualification, and zero derating up to +175 °C junction temperature.
FAQ
What is the polarity configuration of ALS5W18A and how does it affect PCB layout?
ALS5W18A is unidirectional with the heatsink serving as the anode terminal and the cathode identified by a bar marking. This requires the anode to be connected to the protected 12 V rail and the cathode to system ground - PCB layout must allocate a large copper pour under the case for thermal conduction and low-inductance current return path.
Does ALS5W18A require external series impedance for optimal load dump protection?
No - ALS5W18A is designed for direct connection between power rail and ground without series resistance. Its low dynamic impedance and 29.2 V clamping voltage ensure effective protection even with minimal PCB trace inductance, as validated in ISO7637-2 Pulse 5a test setups using 10 Ω source impedance.
How does the DO-218 package improve thermal performance compared to DO-214AB or DO-214AC?
The DO-218 package provides 2.7× greater thermal mass and a metalized heatsink base that enables direct thermal coupling to PCB copper or external heatsinks. Measured RθJC is 0.35 °C/W - significantly lower than DO-214AB (1.2 °C/W) - allowing sustained 3600 W surge dissipation without junction overheating.
Is ALS5W18A suitable for 24 V commercial vehicle applications?
No - ALS5W18A is rated for 18 V stand-off and optimized for 12 V automotive systems. For 24 V platforms, Diodes offers ALS5W36A (36 V VWM) and ALS5W43A (43 V VWM) in the same DO-218 package, maintaining identical thermal, surge, and qualification specifications.
ALS5W18A 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):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 123A
- Power - Peak Pulse:
- 3600W (3.6kW)
- 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
ALS5W18A FAQ
1.How can I place an order for ALS5W18A through Aetrix?
Please submit a Request for Quotation (RFQ) for ALS5W18A 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 ALS5W18A reliable?
The price and inventory of ALS5W18A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ALS5W18A is usually 5 days.
3.What payment methods are accepted for ALS5W18A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ALS5W18A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ALS5W18A?
ALS5W18A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ALS5W18A 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 ALS5W18A?
For technical support, including ALS5W18A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ALS5W18A requirements.
6.How does Aetrix verify that ALS5W18A is sourced from the original manufacturer or authorized distributors?
All ALS5W18A 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 ALS5W18A meets industry standards.
7.What is the process for return or replacement of ALS5W18A?
All ALS5W18A units undergo pre-shipment inspection (PSI). If there is an issue with ALS5W18A, 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 ALS5W18A part is unused and in its original packaging.
Return procedure for ALS5W18A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ALS5W18A Tags
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ESD9B5.0ST5G
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Diodes Incorporated
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Diodes Incorporated
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