Vishay General Semiconductor - Diodes Division SMAJ54A-M3/5A

Overview

SMAJ54A-M3/5A from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode designed for robust overvoltage protection of sensitive electronics. It features a 54 V standoff voltage (V_WM), 60.0–66.3 V breakdown range at 1 mA, clamps transients to ≤87.1 V at 4.6 A peak pulse current, and delivers 400 W peak pulse power (10/1000 μs waveform) in the SMA (DO-214AC) package - deployed on power rails and I/O lines of industrial motor controllers.

For engineers reviewing the SMAJ54A-M3/5A datasheet, SMAJ54A-M3/5A pinout, SMAJ54A-M3/5A application, or SMAJ54A-M3/5A equivalent, key selection criteria include its 54 V working voltage, low 0.01 % duty cycle surge rating, AEC-Q101 qualification eligibility (via HM3 suffix), halogen-free RoHS compliance, and thermal resistance of 120 °C/W junction-to-ambient - critical for high-reliability 24–48 V DC systems.

Technical Context

This unidirectional TVS operates as a clamping device: under normal bias it presents <1 μA leakage at 54 V, but triggers avalanche conduction when reverse voltage exceeds 60.0 V (min), limiting downstream voltage to ≤87.1 V at 4.6 A. Its glass-passivated junction ensures stable breakdown and fast response (<1 ns), while the SMA package supports automated SMT placement with MSL Level 1 moisture sensitivity.

The device is rated for -55 °C to +150 °C operating junction temperature, derates linearly above 25 °C ambient per Fig. 2, and achieves 30 °C/W junction-to-lead thermal resistance - enabling effective heat dissipation when mounted on 5.0 mm × 5.0 mm copper pads per JEDEC standard layout.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, halogen-free, RoHS-compliant, MSL Level 1 (260 °C reflow peak). Cathode indicated by band marking on body.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ54A-E3/5A, the M3 version adds halogen-free compliance for stricter environmental programs; versus SMAJ54CA-M3/5A, the unidirectional configuration provides superior leakage performance (<1 μA vs. ≤2 μA) in grounded 48 V DC systems.

Availability

SMAJ54A-M3/5A is available at Aetrix Electronics and suitable for industrial motor drives, automotive body control modules, telecom power supplies, and PLC digital I/O modules requiring stable component supply with halogen-free compliance and AEC-Q101 qualification path.

Supply support for SMAJ54A-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, efficiency, and application-specific validation.

The SMAJ series is engineered for high-energy transient suppression in harsh environments - targeting automotive, industrial, and telecom systems where robustness against ESD, EFT, and surge events is non-negotiable.

FAQ

What is the maximum clamping voltage of SMAJ54A-M3/5A under surge conditions?

The SMAJ54A-M3/5A clamps to a maximum of 87.1 V when subjected to its rated peak pulse current of 4.6 A (10/1000 μs waveform). This value is measured per ANSI/IEEE C62.35 standards and confirmed in the Vishay datasheet revision 09-Jan-2024. The clamping voltage directly determines the peak stress seen by downstream components, making it a critical parameter for validating protection margins in 48 V systems. SMAJ54A-M3/5A maintains this performance across its full operating temperature range.

Does SMAJ54A-M3/5A meet automotive qualification standards?

SMAJ54A-M3/5A itself is not AEC-Q101 qualified, but the HM3 suffix variant (e.g., SMAJ54A-HM3_X) is explicitly qualified per AEC-Q101. The M3 suffix denotes halogen-free, RoHS-compliant construction - a prerequisite for automotive use - and the underlying die and assembly process are shared with the HM3 grade. For production automotive designs, specify SMAJ54A-HM3_X with appropriate revision code; SMAJ54A-M3/5A serves as the commercial-grade baseline. SMAJ54A-M3/5A supports automotive prototyping and non-safety-critical subsystems.

How does the thermal resistance of SMAJ54A-M3/5A affect PCB layout?

SMAJ54A-M3/5A has a typical junction-to-ambient thermal resistance (R_θJA) of 120 °C/W when mounted on minimum recommended 5.0 mm × 5.0 mm copper pads per JEDEC. To maintain T_J ≤150 °C during repetitive surges, PCB layout must provide adequate copper area and minimize trace length to ground. Increasing pad size or adding internal ground planes reduces R_θJA; failure to meet thermal targets risks parametric shift or premature failure. SMAJ54A-M3/5A's R_θJL of 30 °C/W further emphasizes the need for low-impedance thermal paths to leads.

What is the reverse leakage current of SMAJ54A-M3/5A at its rated standoff voltage?

At its 54 V standoff voltage (V_WM) and 25 °C ambient, SMAJ54A-M3/5A exhibits a maximum reverse leakage current (I_D) of 1.0 μA. This ultra-low leakage preserves system efficiency in always-on applications such as battery-backed sensors or LIN bus nodes. Leakage remains below 5 μA up to 125 °C junction temperature, verified per datasheet Fig. 2 derating curves. SMAJ54A-M3/5A's leakage performance is identical to SMAJ54A-E3/5A and meets stringent requirements for low-power industrial IoT endpoints.

Can SMAJ54A-M3/5A be used in bidirectional signal protection?

No - SMAJ54A-M3/5A is strictly unidirectional and must be oriented with cathode toward the protected line and anode to ground. For bidirectional signal lines (e.g., RS-485, CAN, USB), the SMAJ54CA-M3/5A variant is required, which provides symmetrical clamping in both polarities. Using SMAJ54A-M3/5A on AC or floating signals risks forward conduction during negative excursions, leading to malfunction or damage. SMAJ54A-M3/5A's polarity marking (cathode band) is essential for correct placement; misorientation renders it ineffective.