Vishay General Semiconductor - Diodes Division SMAJ15AHM3_A/I

Overview

SMAJ15AHM3_A/I from Vishay General Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping fast-rising ESD and surge transients on power and signal lines. It features a 15 V standoff voltage (V_WM), 16.7–18.5 V breakdown voltage (V_BR) at 1 mA, 24.4 V maximum clamping voltage (V_C) at 16.4 A peak pulse current, and 400 W peak pulse power rating with 10/1000 μs waveform.

For engineers reviewing the SMAJ15AHM3_A/I datasheet, SMAJ15AHM3_A/I pinout, SMAJ15AHM3_A/I application, or SMAJ15AHM3_A/I equivalent, this device is selected for robust overvoltage protection in automotive-grade power rails, industrial sensor interfaces, and consumer USB/DC-input circuits where AEC-Q101 qualification, low clamping ratio, and MSL Level 1 reflow compatibility are required.

Technical Context

The SMAJ15AHM3_A/I operates as a unidirectional avalanche diode that remains non-conductive below 15 V and enters low-impedance clamping mode within picoseconds when transient voltage exceeds its breakdown threshold. Its glass-passivated junction ensures stable V_BR tolerance (±5%) and low leakage (<1.0 μA at V_WM), while the SMA package supports automated SMT placement and withstands 260 °C peak reflow per J-STD-020.

It delivers 400 W peak pulse power (derated to 300 W above 78 V) under standardized 10/1000 μs surge conditions, with thermal resistance of 120 °C/W (junction-to-ambient) and 30 °C/W (junction-to-lead), enabling reliable operation up to +150 °C junction temperature in compact PCB layouts with minimal copper pad area.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, UL 94 V-0 rated, MSL Level 1, 260 °C peak reflow compatible. Cathode marked by single band on body end.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ15AHM3_A/I, SMAJ15AHE3_A/I omits halogen-free materials and AEC-Q101 validation-making it suitable for cost-sensitive industrial designs-while SMAJ15A-E3/61 matches all electrical behavior but lacks the halogen-free assurance needed for EU automotive Tier 1 programs.

Availability

SMAJ15AHM3_A/I is available at Aetrix Electronics and suitable for automotive electronics, industrial sensor modules, and consumer DC-input protection requiring stable component supply, halogen-free compliance, and AEC-Q101 qualification.

Supply support for SMAJ15AHM3_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 qualification.

The SMAJ series is engineered for high-energy transient suppression in harsh environments, targeting automotive power distribution, industrial control I/O, and consumer power interface protection where fast response, low clamping, and process consistency are critical.

FAQ

What is the maximum clamping voltage of the SMAJ15AHM3_A/I under a 10/1000 μs surge?

The SMAJ15AHM3_A/I has a maximum clamping voltage (V_C) of 24.4 V at 16.4 A peak pulse current (I_PPM) under the standardized 10/1000 μs waveform. This value is guaranteed across temperature and production lot, ensuring consistent overvoltage limiting for protected downstream circuitry such as 16 V-rated regulators or CAN transceivers. The SMAJ15AHM3_A/I achieves this with a clamping ratio of 1.63 relative to its 15 V standoff voltage.

Is the SMAJ15AHM3_A/I qualified for automotive applications?

Yes, the SMAJ15AHM3_A/I is AEC-Q101 qualified, as confirmed by Vishay's ordering code suffix "HM3" (halogen-free, RoHS-compliant, and AEC-Q101 qualified). This qualification covers stress testing for temperature cycling, humidity, mechanical shock, and surge endurance-making the SMAJ15AHM3_A/I suitable for under-hood and cabin applications including body control modules, lighting drivers, and ADAS sensor power rails.

What does the "HM3" suffix indicate in SMAJ15AHM3_A/I?

The "HM3" suffix in SMAJ15AHM3_A/I denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification. Specifically, "H" indicates halogen-free molding compound, "M3" confirms RoHS compliance and JESD201 Class 2 whisker resistance, and the "_A/I" specifies 13" tape-and-reel packaging (7500 pcs) with revision A. This distinguishes it from non-halogen-free variants like SMAJ15AHE3_A/I and ensures compliance with EU automotive material restrictions.

How does the SMAJ15AHM3_A/I compare to bidirectional TVS diodes like SMAJ15CA?

The SMAJ15AHM3_A/I is unidirectional and intended for DC-biased lines where polarity is fixed (e.g., 12 V supply to ground), offering lower leakage (<1.0 μA) and tighter V_BR tolerance than bidirectional counterparts. In contrast, SMAJ15CA provides symmetrical clamping for AC or floating signals but exhibits higher leakage and wider V_BR spread. For 12 V automotive rails, SMAJ15AHM3_A/I delivers superior DC blocking and lower standby current-key for battery-powered modules.

What PCB layout guidance applies to the SMAJ15AHM3_A/I for optimal surge performance?

For optimal surge performance, the SMAJ15AHM3_A/I should be mounted with minimum trace length between cathode and protected line, and anode tied directly to a low-inductance ground plane using ≥5 mm² copper pour per terminal. Vishay specifies 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads for thermal and surge current handling. Avoid routing sensitive traces near the TVS, and place it as close as possible to the connector or IC input to minimize inductance-induced voltage overshoot during fast transients.