Vishay General Semiconductor - Diodes Division SMAJ33AHM3_A/H

Overview

SMAJ33AHM3_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 33 V stand-off voltage (VWM), 53.3 V maximum clamping voltage at 7.5 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 control systems.

For engineers reviewing the SMAJ33AHM3_A/H datasheet, SMAJ33AHM3_A/H pinout, SMAJ33AHM3_A/H application, or SMAJ33AHM3_A/H equivalent, key selection criteria include its unidirectional polarity, AEC-Q101 qualification (via HM3 suffix), 150 °C max junction temperature, low incremental surge resistance, and compatibility with automated SMT placement on 0.2" × 0.2" copper pads.

Technical Context

This TVS diode operates as a fast-acting shunt protector: under normal conditions it presents high impedance (>1 MΩ leakage at 33 V), but triggers into low-impedance conduction when transient voltage exceeds its breakdown range of 36.7–40.6 V (at 1 mA test current). Its glass-passivated junction ensures stable avalanche characteristics and repeatable clamping performance across temperature.

The device complies with IEC 61000-4-2 (ESD), IEC 61000-4-4 (EFT), and ISO 7637-2 (automotive surge) immunity requirements when applied with proper PCB layout. Its MSL Level 1 rating and 260 °C lead-free reflow compatibility support high-reliability manufacturing without preconditioning.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, molded plastic case with matte tin-plated leads; polarity indicated by cathode band on one end.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ33AHM3_A/H, SMAJ33AHE3_A/H offers identical clamping and breakdown but omits halogen-free and AEC-Q101 compliance, while SMBJ33A-H provides greater power handling in a physically larger package - making SMAJ33AHM3_A/H optimal for space-constrained, automotive-qualified designs requiring halogen-free materials.

Availability

SMAJ33AHM3_A/H is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC inputs, and consumer appliance motor control requiring stable component supply with full AEC-Q101 traceability and halogen-free compliance.

Supply support for SMAJ33AHM3_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, rectifiers, MOSFETs, and protection devices with emphasis on reliability, efficiency, and application-specific optimization.

The SMAJ series targets robust transient suppression in harsh environments - engineered for automotive, industrial, and telecom applications where consistent clamping, low leakage, and AEC-Q101 validation are mandatory.

FAQ

What is the clamping voltage of SMAJ33AHM3_A/H at its rated peak pulse current?

The SMAJ33AHM3_A/H has a maximum clamping voltage (VC) of 53.3 V at 7.5 A peak pulse current (IPPM) under the standard 10/1000 μs waveform. This value is measured per JEDEC test conditions and defines the upper voltage limit imposed on protected circuitry during transient events - critical for ensuring downstream ICs remain within absolute maximum ratings. The SMAJ33AHM3_A/H maintains this clamping performance across its full operating temperature range.

Is SMAJ33AHM3_A/H qualified for automotive applications?

Yes, SMAJ33AHM3_A/H is AEC-Q101 qualified, as confirmed by the "HM3" suffix in its ordering code. This qualification covers stress tests including high-temperature reverse bias, temperature cycling, and unbiased highly accelerated stress testing - validating its suitability for under-hood and chassis-mounted automotive modules. The SMAJ33AHM3_A/H meets the reliability requirements for body control units, lighting drivers, and infotainment power supplies.

What does the "HM3" suffix indicate in SMAJ33AHM3_A/H?

The "HM3" suffix in SMAJ33AHM3_A/H denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification. It distinguishes this variant from "HE3" (RoHS + AEC-Q101, not halogen-free) and "E3/M3" (commercial grade only). The "_A/H" further specifies packaging: 7-inch tape-and-reel, 1800-unit quantity, with "A" indicating revision level and "H" denoting the preferred package code per Vishay's ordering matrix.

Can SMAJ33AHM3_A/H be used in bidirectional configurations?

No, SMAJ33AHM3_A/H is a unidirectional TVS diode, as indicated by the "A" (not "CA") suffix and presence of a cathode band. Bidirectional operation requires the "CA" variant (e.g., SMAJ33CA), which exhibits symmetrical breakdown in both polarities. Using SMAJ33AHM3_A/H in reverse-biased configurations risks permanent damage due to forward conduction beyond its 40 A IFSM rating - always verify polarity alignment during PCB layout.

What is the thermal resistance of SMAJ33AHM3_A/H, and how does it affect layout?

SMAJ33AHM3_A/H has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on minimum recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes no additional copper pour or thermal vias; adding thermal relief or stitching vias can reduce RθJA by up to 30 %. Proper thermal design prevents junction temperature from exceeding 150 °C during repetitive surge events - essential for long-term reliability in high-ambient environments.