Vishay General Semiconductor - Diodes Division SMAJ26AHE3_A/I

Overview

SMAJ26AHE3_A/I from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for robust overvoltage protection of DC power rails and signal lines. It features a 26 V standoff voltage (V_WM), 28.9–31.9 V breakdown voltage (V_BR) at 1 mA, 42.1 V maximum clamping voltage (V_C) at 9.5 A peak pulse current, and 400 W peak pulse power rating with 10/1000 μs waveform - deployed in automotive ECUs, industrial sensor interfaces, and USB power input stages.

For engineers reviewing the SMAJ26AHE3_A/I datasheet, SMAJ26AHE3_A/I pinout, SMAJ26AHE3_A/I application, or SMAJ26AHE3_A/I equivalent, key selection criteria include unidirectional polarity, AEC-Q101 qualification, 150 °C max junction temperature, low incremental surge resistance, and compatibility with automated SMT placement on standard PCB pad layouts per JEDEC DO-214AC.

Technical Context

This TVS diode operates as a clamping device: under normal conditions it presents high impedance (>1 μA leakage at 26 V), but triggers into low-impedance conduction when transient voltage exceeds its breakdown threshold. Its glass-passivated junction ensures stable V_BR tolerance (±5%) and fast response time (<1 ns), critical for protecting sensitive MOSFET gates and microcontroller I/O pins against ESD and inductive switching spikes.

The SMAJ26AHE3_A/I is rated for 40 A non-repetitive forward surge current (I_FSM, 8.3 ms half-sine), supports 3.3 W steady-state power dissipation, and exhibits a positive temperature coefficient of V_BR (+0.097 %/°C), enabling predictable derating above 25 °C ambient per Fig. 2 in the datasheet.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), molded plastic case with cathode band marking; terminals are matte tin-plated, solderable per J-STD-002 and JESD 22-B102.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient voltage suppression applications.

Compared with SMAJ26AHE3_A/I, SMAJ26A-E3/61 offers identical clamping performance at lower cost but lacks automotive qualification, while SMCJ26AHE3_A/I delivers 3.75× higher surge power in a physically larger package - requiring layout revision but enabling robustness in high-energy automotive subsystems.

Availability

SMAJ26AHE3_A/I is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC input protection, and USB-C power delivery adapter designs requiring stable component supply, AEC-Q101 compliance, and consistent DO-214AC packaging.

Supply support for SMAJ26AHE3_A/I 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

Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, rectifiers, MOSFETs, and protection devices with emphasis on reliability, precision, and automotive-grade validation.

The SMAJ series is engineered specifically for board-level transient suppression in harsh environments - balancing high surge capability, tight V_BR tolerance, and AEC-Q101 qualification for automotive and industrial control applications.

FAQ

What is the maximum clamping voltage of SMAJ26AHE3_A/I at its rated peak pulse current?

The SMAJ26AHE3_A/I has a maximum clamping voltage (V_C) of 42.1 V at its specified peak pulse current (I_PPM) of 9.5 A, measured using the standardized 10/1000 μs double-exponential waveform. This value is guaranteed across the full operating temperature range and defines the upper voltage limit imposed on protected circuitry during transient events. The SMAJ26AHE3_A/I maintains this clamping performance with low dynamic impedance, ensuring effective protection for 36 V-rated downstream components.

Is SMAJ26AHE3_A/I suitable for automotive applications?

Yes, SMAJ26AHE3_A/I is AEC-Q101 qualified, meaning it has passed rigorous stress tests including high-temperature reverse bias, high-temperature operating life, and temperature cycling - all required for automotive electronic components. Its 150 °C maximum junction temperature, stable V_BR coefficient (+0.097 %/°C), and DO-214AC package with MSL Level 1 rating make it appropriate for under-hood and cabin-mounted modules. The SMAJ26AHE3_A/I is explicitly designated for automotive use in Vishay's ordering nomenclature via the "HE3" suffix.

How does the unidirectional configuration of SMAJ26AHE3_A/I affect its circuit placement?

The unidirectional configuration of SMAJ26AHE3_A/I requires correct polarity orientation: the cathode (marked by a band) must connect toward the protected line (e.g., 24 V rail), and the anode to ground. This allows it to conduct only during positive transients relative to ground, making it ideal for DC power rail protection. Unlike bidirectional variants, SMAJ26AHE3_A/I blocks reverse voltage beyond its V_WM, so it cannot be used on AC or floating signal lines without additional circuitry. Proper orientation ensures optimal clamping and prevents unintended conduction during normal operation.

What is the thermal resistance of SMAJ26AHE3_A/I, and how does it impact PCB layout?

SMAJ26AHE3_A/I has a typical junction-to-ambient thermal resistance (R_θJA) of 120 °C/W and junction-to-lead (R_θJL) of 30 °C/W when mounted on the recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. To maintain safe junction temperatures under sustained power dissipation, PCB layout must provide adequate copper area and avoid thermal isolation. For intermittent 400 W surges, thermal mass dominates; however, for repetitive events or elevated ambient temperatures, increasing pad size or adding internal planes improves heat spreading. The SMAJ26AHE3_A/I's R_θJA value assumes JEDEC-standard mounting - deviations require derating per Fig. 2 in the datasheet.

Does SMAJ26AHE3_A/I meet any industry surge immunity standards out-of-the-box?

SMAJ26AHE3_A/I is designed to meet key surge immunity standards when applied per Vishay's recommended layout: its 400 W (10/1000 μs) rating aligns with IEC 61000-4-5 Level 3 (1 kV line-earth, 2 kV line-line) for 24 V systems, and its 40 A I_FSM supports ISO 7637-2 Pulse 1 (inductive switch-off) and Pulse 2a (battery disconnect). While not certified to these standards individually, the SMAJ26AHE3_A/I is widely adopted in designs passing those tests - especially when combined with proper series impedance and grounding. System-level validation remains the responsibility of the end designer, but the SMAJ26AHE3_A/I provides the foundational clamping performance required.