Vishay General Semiconductor - Diodes Division SMAJ24A-M3/5A

Overview

SMAJ24A-M3/5A from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode designed for robust overvoltage protection in DC power rails and signal lines. It features a 24 V standoff voltage (V_WM), 26.7–29.5 V breakdown range at 1 mA, clamps transients to ≤38.9 V at 10.3 A peak pulse current (10/1000 μs), and delivers 400 W peak pulse power - optimized for automotive and industrial electronics exposed to load-switching surges and ESD.

For engineers reviewing the SMAJ24A-M3/5A datasheet, SMAJ24A-M3/5A pinout, SMAJ24A-M3/5A application, or SMAJ24A-M3/5A equivalent, key selection criteria include its unidirectional polarity, SMA (DO-214AC) package compatibility with automated placement, AEC-Q101 qualification readiness (via HM3 suffix variants), low clamping ratio (VC/V_BR ≈ 1.4), and 0.096 %/°C temperature coefficient of breakdown voltage.

Technical Context

This TVS diode operates as a clamping device in parallel with protected circuitry, entering avalanche conduction when reverse voltage exceeds V_BR. Its glass-passivated junction ensures stable leakage (<1.0 μA at 24 V) and fast response time (<1 ns), enabling suppression of fast-rising transients from inductive switching or ESD events.

The device is rated for 40 A non-repetitive forward surge current (8.3 ms half-sine), supports continuous power dissipation of 3.3 W on infinite heatsink at 50 °C, and exhibits thermal resistance of 120 °C/W (junction-to-ambient) and 30 °C/W (junction-to-lead) - confirming suitability for compact PCB layouts with limited copper area.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, molded plastic case with matte tin-plated leads. Cathode indicated by a band on the body; anode is unmarked end. Meets UL 94 V-0 flammability rating and JESD 201 Class 2 whisker resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ24A-M3/5A, the E3 variant offers identical protection performance at lower cost for non-automotive use, while the HM3_A/I variant adds AEC-Q101 validation and larger reel packaging - making it suitable for Tier 1 automotive supply chains where qualification and volume logistics are critical.

Availability

SMAJ24A-M3/5A is available at Aetrix Electronics and suitable for automotive electronic control units, industrial sensor interfaces, and telecom power entry circuits requiring stable component supply with halogen-free compliance and MSL Level 1 reflow capability.

Supply support for SMAJ24A-M3/5A 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, TVS devices, and optoelectronics with emphasis on reliability, power efficiency, and AEC-Q qualification.

The SMAJ series is engineered specifically for high-reliability transient suppression in harsh environments - targeting automotive, industrial, and telecom applications where robustness against load dump, ESD, and lightning-induced surges is mission-critical.

FAQ

What is the clamping voltage of the SMAJ24A-M3/5A under peak surge conditions?

The SMAJ24A-M3/5A clamps to a maximum of 38.9 V when subjected to a 10.3 A peak pulse current with a 10/1000 μs waveform. This value is measured per JEDEC standards and guarantees protection for downstream components rated up to 40 V, such as automotive-grade microcontrollers and gate drivers. The clamping voltage is confirmed in the Vishay datasheet Document Number 88390, Table on page 2.

Is the SMAJ24A-M3/5A suitable for automotive applications?

The SMAJ24A-M3/5A itself is not AEC-Q101 qualified, but it shares identical electrical and thermal specifications with the AEC-Q101-qualified variant SMAJ24AHM3_A/I. As a halogen-free, RoHS-compliant part with MSL Level 1 rating and 150 °C junction temperature capability, SMAJ24A-M3/5A is widely used in non-safety-critical automotive subsystems - though formal qualification requires the HM3_X suffix version.

What does the "M3" suffix indicate in SMAJ24A-M3/5A?

The "M3" suffix in SMAJ24A-M3/5A denotes halogen-free, RoHS-compliant construction with matte tin-plated leads meeting J-STD-002 solderability and JESD 201 Class 2 whisker resistance. It distinguishes this variant from the "E3" (RoHS only) and "HM3" (AEC-Q101 + halogen-free) versions - all sharing identical TVS performance but differing in material compliance and qualification scope.

How does the SMAJ24A-M3/5A compare to bidirectional TVS diodes like SMAJ24CA?

The SMAJ24A-M3/5A is unidirectional and must be oriented with cathode toward the protected line; SMAJ24CA is bidirectional and symmetrical, suitable for AC or floating signal lines. SMAJ24A-M3/5A offers lower leakage (<1.0 μA at 24 V) and is preferred for DC power rail protection, whereas SMAJ24CA provides equal clamping in both directions but with higher leakage at low bias - making SMAJ24A-M3/5A the correct choice for 24 V supply line hardening.

What PCB pad layout is recommended for optimal thermal performance of the SMAJ24A-M3/5A?

Vishay specifies a minimum 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pad per terminal for rated 400 W pulse power. The SMAJ24A-M3/5A's thermal resistance is 120 °C/W (junction-to-ambient) under these conditions; reducing pad size increases junction temperature and may require derating. Layout should follow the DO-214AC outline in the datasheet Figure on page 5, including cathode band alignment and solder mask clearance.