Vishay General Semiconductor - Diodes Division SMAJ17AHM3_A/H

Overview

SMAJ17AHM3_A/H from Vishay General Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping voltage transients on power and signal lines. It features a 17 V standoff voltage (V_WM), 18.9–20.9 V breakdown voltage (V_BR) at 1 mA, 27.6 V maximum clamping voltage (V_C) at 14.5 A peak pulse current, and 400 W peak pulse power rating with 10/1000 μs waveform - used to protect MOSFETs, ICs, and sensor interfaces in automotive and industrial power rails.

For engineers reviewing the SMAJ17AHM3_A/H datasheet, SMAJ17AHM3_A/H pinout, SMAJ17AHM3_A/H application, or SMAJ17AHM3_A/H equivalent, this device is selected for robust ESD and surge protection where low-profile SMT placement, AEC-Q101 qualification, and stable clamping under repetitive transients are required - especially in 12 V/24 V DC systems with IFSM = 40 A surge tolerance and TJ max = 150 °C operation.

Technical Context

The SMAJ17AHM3_A/H operates as a unidirectional avalanche diode, conducting only when reverse voltage exceeds its V_BR threshold (18.9–20.9 V), then clamping to ≤27.6 V at 14.5 A. Its glass-passivated junction ensures stable leakage (<1.0 μA at V_WM) and fast response (<1 ns), critical for protecting sensitive CMOS inputs and gate drivers.

Rated for 400 W peak pulse power (10/1000 μs) up to 78 V and derated to 300 W above that, it supports repetitive surge events at 0.01% duty cycle. The device meets MSL Level 1 per J-STD-020, with matte tin-plated leads solderable per J-STD-002, and is halogen-free and RoHS-compliant (HM3 suffix).

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, low-profile case with cathode band marking on unidirectional types. Dimensions: 4.50 mm × 2.79 mm × 2.29 mm (L × W × H), compliant with IPC-7351B footprint standards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ17AHM3_A/H, SMAJ17AHE3_A/H offers identical protection performance without halogen-free or automotive qualification, while SMBJ17A-HM3 trades compactness for higher pulse power and thermal resistance - making SMAJ17AHM3_A/H optimal for AEC-Q101–required, space-limited 12–24 V systems.

Availability

SMAJ17AHM3_A/H is available at Aetrix Electronics and suitable for automotive ECUs, industrial sensor nodes, and consumer power adapters requiring stable component supply with halogen-free, AEC-Q101–qualified TVS protection.

Supply support for SMAJ17AHM3_A/H 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, MOSFETs, optoelectronics, and passive components with emphasis on reliability and application-specific performance.

The SMAJ series is engineered for high-reliability transient suppression in harsh environments - targeting automotive, industrial, and telecom infrastructure where consistent clamping, low leakage, and long-term stability are mandatory.

FAQ

What is the clamping voltage of SMAJ17AHM3_A/H at its rated peak pulse current?

The SMAJ17AHM3_A/H has a maximum clamping voltage (V_C) of 27.6 V at its specified peak pulse current (I_PPM) of 14.5 A, measured using the standardized 10/1000 μs double-exponential surge waveform. This value defines the upper voltage limit imposed on protected circuitry during transient events and is confirmed in Vishay's datasheet revision 09-Jan-2024, page 2. The SMAJ17AHM3_A/H maintains this clamping performance across its full operating temperature range (−55 °C to +150 °C).

Is SMAJ17AHM3_A/H qualified for automotive applications?

Yes, SMAJ17AHM3_A/H is AEC-Q101 qualified, as indicated by the "HM3" suffix and confirmed in the Vishay datasheet (page 3, Note 1). This qualification covers stress tests including high-temperature reverse bias (HTRB), temperature cycling, and unbiased highly accelerated stress testing (UHAST), validating its suitability for under-hood and chassis-mounted automotive electronics. The SMAJ17AHM3_A/H is explicitly designated for automotive use in the ordering information table.

What does the "HM3" suffix signify in SMAJ17AHM3_A/H?

The "HM3" suffix in SMAJ17AHM3_A/H denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification - distinguishing it from "E3" (RoHS-compliant only) and "HE3" (AEC-Q101 + RoHS, but not halogen-free) variants. Per Vishay's ordering table (page 3), HM3 devices meet JESD201 Class 2 whisker resistance and UL 94 V-0 flammability standards, making SMAJ17AHM3_A/H appropriate for environmentally regulated automotive and industrial deployments.

Can SMAJ17AHM3_A/H be used in bidirectional configurations?

No, SMAJ17AHM3_A/H is a unidirectional TVS diode, as confirmed by its part number ending in "A" (not "CA") and the presence of a cathode band marking. Bidirectional operation requires the "CA" suffix (e.g., SMAJ17CA), which exhibits symmetrical breakdown in both polarities. Using SMAJ17AHM3_A/H in reverse-biased signal lines would result in forward conduction and failure; always verify polarity during layout placement.

What is the maximum printed circuit board pad size recommended for SMAJ17AHM3_A/H thermal performance?

Vishay specifies that the 400 W peak pulse power rating for SMAJ17AHM3_A/H is validated when mounted on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal, as stated in the "Maximum Ratings" table (page 1). Reducing pad size increases thermal resistance and reduces surge capability - for example, halving pad area may reduce I_PPM by ~20 %. The SMAJ17AHM3_A/H's R_θJA of 120 °C/W assumes this minimum pad layout.