Diodes Incorporated ALS5W26A

Overview

ALS5W26A from Diodes Incorporated is a unidirectional surface-mount load dump transient voltage suppressor in DO-218 package, rated for 26 V stand-off voltage (V_WM), 28.9–31.9 V breakdown (V_BR), 42.1 V clamping at 86 A peak pulse current, and 3600 W peak pulse power (10/1000 µs). It serves as a clamping diode for automotive ECU load dump protection, meeting ISO7637-2 and ISO16750-2 surge standards.

For engineers reviewing the ALS5W26A datasheet, ALS5W26A pinout, ALS5W26A application, or ALS5W26A equivalent, key selection factors include its 26 V V_WM, 42.1 V clamping voltage at 86 A, DO-218 thermal performance (T_J = −55 to +175 °C), AEC-Q101 qualification, and unidirectional polarity with heatsink-anode configuration.

Technical Context

This TVS diode operates in avalanche breakdown mode during transients, delivering fast response (<1 ns) to inductive switching surges. Its unidirectional structure enables robust forward conduction during load dump events while maintaining low reverse leakage (<10 µA at V_WM) across temperature.

The DO-218 package provides low thermal resistance (R_θJC ≈ 1.0 °C/W typical) and high-power dissipation capability, supporting sustained operation up to 175 °C junction temperature. It is designed specifically for automotive 12 V system protection where high peak power (3600 W) and stable clamping under thermal stress are required.

Key Specifications

Pinout & Package

ALS5W26A uses the DO-218 plastic package with heatsink-anode polarity: the metal tab (heatsink) is the anode terminal, and the molded cathode band identifies the cathode lead. This configuration enables direct mounting to PCB copper pour for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ26A and SMCJ26A, ALS5W26A uniquely combines 3600 W surge capability, AEC-Q101 qualification, and DO-218 thermal performance-making it the only option validated for under-hood automotive load dump protection per ISO7637-2.

Availability

ALS5W26A is available at Aetrix Electronics and suitable for automotive engine control units, LED lighting drivers, body control modules, and start-stop system interfaces requiring stable component supply and full automotive qualification traceability.

Supply support for ALS5W26A 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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

ALS5W26A belongs to Diodes' Automotive TVS Diode family, engineered specifically for high-energy load dump suppression in 12 V vehicle electrical systems, emphasizing thermal robustness, AEC-Q101 compliance, and ISO standard conformance.

FAQ

What is the polarity configuration of ALS5W26A and how does it affect PCB layout?

The ALS5W26A is unidirectional with the heatsink tab as the anode and the banded lead as the cathode. This requires the tab to be connected to the protected supply rail (e.g., battery+) and the cathode to ground or a low-impedance return path. PCB layout must allocate ≥200 mm² copper pour under the tab for thermal dissipation and ensure no isolation gaps interrupt current flow to the heatsink plane.

Does ALS5W26A meet ISO7637-2 Pulse 5a requirements out-of-the-box?

Yes - ALS5W26A is tested and specified to withstand ISO7637-2 Pulse 5a (12 V system: 100 V, 100 ms, R_S = 1 Ω) without parameter shift or failure. Its 3600 W peak power rating and 42.1 V clamping voltage ensure the protected circuit sees <45 V during the surge, satisfying the standard's voltage-limiting requirement for Class III devices.

How does the DO-218 package improve thermal performance over DO-214AB in high-power TVS applications?

The DO-218 package features a larger metal tab area and optimized internal bond wire geometry, achieving ~1.0 °C/W junction-to-case thermal resistance versus ~2.5 °C/W for DO-214AB. This allows ALS5W26A to sustain 3600 W surges with <100 °C temperature rise from case to junction - critical for repeated load dump events in high-ambient under-hood locations.

Can ALS5W26A be used in 24 V commercial vehicle systems?

No - ALS5W26A is rated for 26 V stand-off and intended for 12 V automotive systems. For 24 V systems, Diodes offers ALS5W43A (43 V V_WM, 69.4 V V_C) which meets ISO7637-2 Pulse 5b (24 V system: 200 V, 100 ms). Using ALS5W26A in 24 V applications risks premature clamping and excessive power dissipation during normal operation.