Vishay General Semiconductor - Diodes Division SMBJ30A-M3/5B

Overview

SMBJ30A-M3/5B from Vishay General Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for robust overvoltage protection of sensitive electronics. It features a 30 V standoff voltage (V_WM), 33.3–36.8 V breakdown voltage (V_BR) at 1 mA, and clamps transients to ≤48.4 V at 12.4 A peak pulse current (I_PPM) under 10/1000 µs waveform - deployed on power rails and signal lines in industrial motor drives and automotive ECUs.

For engineers reviewing the SMBJ30A-M3/5B datasheet, SMBJ30A-M3/5B pinout, SMBJ30A-M3/5B application, or SMBJ30A-M3/5B equivalent, key selection criteria include its 600 W peak pulse power rating, low 0.099 %/°C V_BR temperature coefficient, halogen-free RoHS-compliant construction (M3 suffix), and SMB (DO-214AA) package compatibility with automated SMT assembly.

Technical Context

This TVS diode operates as a unidirectional clamping device, conducting only when reverse voltage exceeds its specified breakdown threshold. Its glass-passivated junction ensures stable leakage performance (<1.0 µA at V_WM) and fast response time (<1.0 ns), enabling effective suppression of ESD, lightning-induced surges, and inductive switching transients.

The SMBJ30A-M3/5B is rated for 100 A non-repetitive forward surge current (I_FSM, 8.3 ms half-sine) and operates across –55 °C to +150 °C junction temperature range. Thermal resistance is 100 °C/W (junction-to-ambient, on 0.2" × 0.2" copper pads), supporting reliable operation in thermally constrained PCB layouts without forced cooling.

Key Specifications

Pinout & Package

Package: SMB (DO-214AA), surface-mount, unidirectional polarity indicated by cathode band. Matte tin-plated leads meet J-STD-002 solderability and JESD 22-B102 whisker resistance Class 2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ30A-E3/5B, the SMBJ30A-M3/5B adds halogen-free compliance without sacrificing surge rating or thermal performance; versus SMBJ30CA-M3/5B, it provides optimized clamping for DC rails but lacks bidirectional symmetry - making it unsuitable for AC or differential bus protection.

Availability

SMBJ30A-M3/5B is available at Aetrix Electronics and suitable for industrial motor drives, automotive engine control units, and telecom power supplies requiring stable component supply, long-term lifecycle support, and consistent halogen-free material compliance.

Supply support for SMBJ30A-M3/5B 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 qualification.

The SMBJ series is engineered for high-energy transient suppression in harsh environments, targeting automotive, industrial, and telecom applications where robustness, AEC-Q101 readiness, and precise clamping performance are critical.

FAQ

What is the maximum clamping voltage of the SMBJ30A-M3/5B under a 10/1000 µs surge?

The SMBJ30A-M3/5B clamps to a maximum of 48.4 V when subjected to its rated 12.4 A peak pulse current (I_PPM) under the standard 10/1000 µs waveform. This value is measured and guaranteed per Vishay's datasheet (Document Number: 88392, Rev. 09-Jan-2024), and defines the upper voltage limit imposed on protected circuitry during surge events. The SMBJ30A-M3/5B maintains this clamping performance across its full operating temperature range.

Does the SMBJ30A-M3/5B meet automotive qualification standards?

The SMBJ30A-M3/5B is halogen-free and RoHS-compliant per its M3 suffix, but it is not AEC-Q101 qualified. For automotive applications requiring AEC-Q101, Vishay offers the HM3-suffixed variant (e.g., SMBJ30A-HM3/5B). The SMBJ30A-M3/5B remains suitable for non-safety-critical automotive subsystems where commercial-grade reliability suffices, and its 150 °C T_J max supports under-hood ambient conditions. Always verify qualification status via the specific ordering code.

How does the SMBJ30A-M3/5B differ from the SMBJ30CA-M3/5B?

The SMBJ30A-M3/5B is unidirectional, with a cathode band indicating polarity and clamping only during reverse overvoltage; the SMBJ30CA-M3/5B is bidirectional, offering symmetrical clamping in both directions and no polarity marking. Their V_BR and V_C values are identical, but the SMBJ30CA-M3/5B is required for AC-coupled or differential lines (e.g., RS-485), whereas the SMBJ30A-M3/5B is optimized for DC rail protection. They are not pin-compatible replacements.

What is the thermal resistance of the SMBJ30A-M3/5B, and how does it affect layout design?

The SMBJ30A-M3/5B has a typical junction-to-ambient thermal resistance (R_θJA) of 100 °C/W when mounted on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes minimum recommended pad layout per Vishay's datasheet; reducing pad area increases R_θJA, potentially limiting power dissipation. To sustain repetitive surges, designers should maintain full copper exposure and avoid excessive trace length or thermal isolation. The SMBJ30A-M3/5B's R_θJL of 20 °C/W further supports heat transfer to PCB copper planes.

Is the SMBJ30A-M3/5B suitable for protecting 3.3 V or 5 V logic circuits directly?

No - the SMBJ30A-M3/5B is not suitable for direct protection of 3.3 V or 5 V logic circuits due to its 30 V standoff voltage (V_WM) and 33.3–36.8 V breakdown range. Using it on low-voltage rails would allow damaging overvoltages to pass unclamped. For 3.3 V/5 V I/O protection, select lower-V_WM TVS devices such as SMBJ5.0A-M3/5B (V_WM = 5.0 V). The SMBJ30A-M3/5B is intended for 24–32 V system rails, motor drive supplies, or auxiliary power domains.