Diodes Incorporated ALS6W18A

Overview

ALS6W18A from Diodes Incorporated is a unidirectional surface-mount load dump transient voltage suppressor in DO-218 package, rated for 18.0 V standoff voltage, 20.0–22.1 V breakdown voltage at 5 mA, 4600 W peak pulse power (10/1000 µs), and 600 A forward surge current. It serves as a clamping diode for automotive ECU modules to protect sensitive electronics against ISO 7637-2 and ISO 16750-2 load dump transients.

For engineers reviewing the ALS6W18A datasheet, ALS6W18A pinout, ALS6W18A application, or ALS6W18A equivalent, key selection criteria include its 29.2 V clamping voltage at 158 A, AEC-Q101 qualification, MSL Level 1 rating, 175 °C max junction temperature, and DO-218 thermal performance with heatsink-anode polarity.

Technical Context

The ALS6W18A operates as a unidirectional TVS diode optimized for high-energy automotive load dump suppression. Its silicon design delivers low forward voltage drop (≤1.9 V at 100 A), low reverse leakage (≤10 µA at 18.0 V and 25 °C; ≤150 µA at 175 °C), and stable clamping behavior across -55 °C to +175 °C.

It meets ISO 7637-2 Pulse 5a/b and ISO 16750-2 load dump test profiles using exponential waveforms up to 10 ms. The DO-218 package provides low thermal resistance and high-temperature soldering capability (260 °C/10 s), with anode-connected heatsink enabling efficient heat dissipation during repetitive surge events.

Key Specifications

Pinout & Package

DO-218 plastic package with heatsink-anode polarity: anode terminal connected to molded heatsink tab; cathode marked by bar on body. Matte tin-plated terminals compliant with MIL-STD-750 Method 2026 and JESD 22-B102.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar load dump suppression applications.

Compared with SMAJ18A and SMCJ18A, the ALS6W18A delivers 3× higher surge energy handling, automotive-grade thermal and reliability validation, and DO-218 mechanical robustness-making it the sole choice for primary load dump protection in production ECU designs.

Availability

ALS6W18A is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS domain controllers, and infotainment systems requiring stable component supply across automotive production lifecycles.

Supply support for ALS6W18A 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 power management, signal integrity, and protection solutions.

The ALS6WxxA series belongs to Diodes' automotive-grade TVS portfolio, engineered specifically for ISO-compliant load dump suppression in 12 V vehicle electrical systems with emphasis on thermal stability and surge endurance.

FAQ

What is the maximum clamping voltage of ALS6W18A under standard load dump test conditions?

The ALS6W18A clamps to 29.2 V at 158 A under the 10/1000 µs double-exponential waveform, as verified per IEC 61000-4-5 and ISO 7637-2 test methods. This value is measured at T_A = 25 °C with specified mounting on 1-inch² 2-oz copper; actual clamping may rise slightly at elevated case temperatures due to positive V_BR temperature coefficient.

Is ALS6W18A suitable for 24 V commercial vehicle applications?

No - ALS6W18A is specified for 12 V nominal systems with 18.0 V standoff. For 24 V systems, Diodes offers ALS6W36A (36.0 V V_WM) and ALS6W43A (43.0 V V_WM) in the same DO-218 package, both sharing identical surge ratings, thermal performance, and AEC-Q101 qualification.

How does the DO-218 package improve thermal performance compared to SMA or SMC?

The DO-218 package features an integrated heatsink tab directly bonded to the anode, reducing thermal resistance from junction-to-case (R_θJC) to 0.35 °C/W - approximately 40% lower than SMCJ devices. This allows sustained 4600 W pulse handling without derating below 125 °C case temperature, critical for under-hood ECU placement.

Does ALS6W18A require external heat sinking beyond PCB copper?

For single-pulse load dump events, the DO-218 anode tab mounted to ≥1-inch² 2-oz copper achieves sufficient cooling. However, for repetitive surges (>1 Hz) or ambient >105 °C, Diodes recommends adding a bolted aluminum heatsink to the tab per Figure 1 derating curve - enabling full 4600 W capability up to 150 °C case temperature.