Vishay General Semiconductor - Diodes Division SMAJ43A-M3/5A

Overview

SMAJ43A-M3/5A 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 43 V standoff voltage (V_WM), 47.8–52.8 V breakdown voltage (V_BR) at 1 mA, 69.4 V maximum clamping voltage (V_C) at 5.8 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 supplies.

For engineers reviewing the SMAJ43A-M3/5A datasheet, SMAJ43A-M3/5A pinout, SMAJ43A-M3/5A application, or SMAJ43A-M3/5A equivalent, key selection criteria include unidirectional polarity, 150 °C max junction temperature, MSL Level 1 moisture sensitivity, halogen-free RoHS compliance (M3 suffix), and compatibility with automated SMT placement on 0.2" × 0.2" copper pads.

Technical Context

This TVS diode operates as a fast-acting shunt clamp during overvoltage events, leveraging an avalanche breakdown mechanism to divert surge current away from protected circuitry. Its low incremental surge resistance and sub-nanosecond response time ensure effective suppression of ESD, lightning-induced surges, and inductive switching transients.

The device is rated for 40 A non-repetitive forward surge current (I_FSM) and dissipates up to 3.3 W continuously at 50 °C ambient on infinite heatsink. Thermal resistance is 120 °C/W junction-to-ambient (R_θJA) and 30 °C/W junction-to-lead (R_θJL), supporting reliable operation in compact PCB layouts with defined pad thermal relief.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, UL 94 V-0 rated compound, polarity indicated by cathode band on unidirectional types.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ43A-M3/5A, the E3 variant offers identical protection performance at lower cost for non-automotive use, while the HE3 variant adds AEC-Q101 validation for mission-critical vehicle subsystems - both share the same SMA package, thermal profile, and clamping behavior.

Availability

SMAJ43A-M3/5A is available at Aetrix Electronics and suitable for automotive power management, industrial sensor interface design, and telecom DC feeding applications requiring stable component supply, halogen-free compliance, and SMT manufacturability.

Supply support for SMAJ43A-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, MOSFETs, and protection devices with emphasis on reliability, power efficiency, and automotive-grade qualification.

The SMAJ series is engineered for high-energy transient suppression in harsh environments, targeting automotive, industrial, and telecom infrastructure where robustness, consistency, and regulatory compliance are mandatory.

FAQ

What is the standoff voltage rating of the SMAJ43A-M3/5A?

The SMAJ43A-M3/5A has a maximum reverse standoff voltage (V_WM) of 43 V, meaning it remains non-conductive under normal operating conditions up to this DC or RMS voltage level. This value is critical for ensuring no leakage current or unintended conduction during steady-state operation while still enabling rapid clamping above this threshold. The SMAJ43A-M3/5A maintains <1.0 μA reverse leakage at 43 V and 25 °C.

Does the SMAJ43A-M3/5A meet automotive qualification standards?

The SMAJ43A-M3/5A itself is commercial-grade and halogen-free (M3 suffix), but not AEC-Q101 qualified. However, Vishay offers the functionally identical SMAJ43AHE3_A/I variant with full AEC-Q101 qualification for automotive use. The SMAJ43A-M3/5A shares the same die, package, and electrical characteristics - only the test documentation and traceability differ. For non-automotive industrial or telecom applications, SMAJ43A-M3/5A is fully suitable.

What is the clamping voltage of the SMAJ43A-M3/5A under surge conditions?

The SMAJ43A-M3/5A clamps to a maximum of 69.4 V when subjected to its rated 5.8 A peak pulse current (I_PPM) using the standard 10/1000 μs waveform. This clamping voltage represents the highest voltage that will appear across the protected circuit during a surge event. It is measured at the device terminals and directly determines the overvoltage stress imposed on downstream components like microcontrollers or transceivers.

Can the SMAJ43A-M3/5A be used in bidirectional configurations?

No - the SMAJ43A-M3/5A is strictly unidirectional, as indicated by the "A" suffix and cathode band marking. Bidirectional versions carry the "CA" suffix (e.g., SMAJ43CA). Using SMAJ43A-M3/5A in a bidirectional application would result in forward conduction during negative transients, potentially damaging the device or failing to protect the circuit. For AC or dual-polarity signal lines, SMAJ43CA-M3/5A must be selected instead.

What is the thermal resistance and power dissipation capability of the SMAJ43A-M3/5A?

The SMAJ43A-M3/5A has a typical junction-to-ambient thermal resistance (R_θJA) of 120 °C/W and junction-to-lead resistance (R_θJL) of 30 °C/W. Its steady-state power dissipation (P_D) is rated at 3.3 W at 50 °C ambient with infinite heatsink conditions. In practice, on standard 0.2" × 0.2" copper pads, derating applies above 25 °C ambient - the SMAJ43A-M3/5A remains functional up to +150 °C junction temperature.