Vishay General Semiconductor - Diodes Division SMBJ45A-M3/5B

Overview

SMBJ45A-M3/5B from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode in SMB (DO-214AA) package, designed for robust overvoltage protection of DC power rails and signal lines. It features a 45 V stand-off voltage (V_WM), 50.0–55.3 V breakdown voltage (V_BR) at 1 mA, 72.7 V maximum clamping voltage (V_C) at 8.3 A peak pulse current, and 600 W peak pulse power rating with 10/1000 µs waveform - deployed in industrial sensor interfaces and automotive ECUs.

For engineers reviewing the SMBJ45A-M3/5B datasheet, SMBJ45A-M3/5B pinout, SMBJ45A-M3/5B application, or SMBJ45A-M3/5B equivalent, key selection criteria include clamping performance under 8.3 A surge, thermal resistance (R_θJA = 100 °C/W), halogen-free RoHS compliance (M3 suffix), and unidirectional polarity with cathode band marking.

Technical Context

This TVS diode operates as a voltage-clamped shunt protector: when reverse voltage exceeds V_WM = 45 V, it avalanches to limit transient energy by diverting surge current to ground. Its glass-passivated junction ensures stable breakdown and low leakage (<1.0 µA at V_WM).

Designed for automated SMT placement on PCBs with 0.2" × 0.2" copper pads per terminal, it supports repetitive surge duty cycles up to 0.01 % and meets MSL Level 1 (peak reflow ≤ 260 °C). Junction temperature range is –55 °C to +150 °C.

Key Specifications

Pinout & Package

Package: SMB (DO-214AA), unidirectional configuration with cathode indicated by molded band. Terminals are anode (unmarked end) and cathode (banded end).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TVS diode applications.

Compared with SMBJ45A-M3/5B, the E3 variant trades halogen-free status for lower unit cost in non-automotive applications, while the HM3_B/I variant adds AEC-Q101 qualification and different packaging - neither is pin-compatible drop-in replacement due to differing qualification scope and reel configuration.

Availability

SMBJ45A-M3/5B is available at Aetrix Electronics and suitable for industrial sensor interfaces, automotive body control modules, telecom power supplies, and consumer USB-C power delivery ports requiring stable component supply and halogen-free compliance.

Supply support for SMBJ45A-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, MOSFETs, optoelectronics, and passive components with emphasis on reliability and high-volume manufacturability.

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

FAQ

What is the clamping voltage of SMBJ45A-M3/5B at its rated peak pulse current?

The SMBJ45A-M3/5B has a maximum clamping voltage (V_C) of 72.7 V at 8.3 A peak pulse current (I_PPM) under 10/1000 µs waveform conditions. This value is measured per JEDEC standards and defines the upper voltage limit imposed on protected circuitry during surge events. The SMBJ45A-M3/5B maintains this clamping performance across its specified operating temperature range of –55 °C to +150 °C.

Is SMBJ45A-M3/5B suitable for automotive applications?

SMBJ45A-M3/5B is halogen-free and RoHS-compliant but not AEC-Q101 qualified. For automotive use, Vishay offers the SMBJ45AHM3_B/I variant, which carries AEC-Q101 qualification and full PPAP documentation. The SMBJ45A-M3/5B may be used in non-safety-critical automotive subsystems where qualification is not mandated, but design validation per ISO 16750-2 remains the customer's responsibility.

What does the "M3" suffix indicate in SMBJ45A-M3/5B?

The "M3" suffix in SMBJ45A-M3/5B denotes halogen-free, RoHS-compliant construction meeting IPC-1752A material declaration requirements. It also signifies compliance with JESD201 Class 2 whisker resistance and J-STD-020 MSL Level 1 moisture sensitivity. This distinguishes it from the "E3" variant, which is RoHS-compliant but not halogen-free.

How is the polarity marked on SMBJ45A-M3/5B?

SMBJ45A-M3/5B is a unidirectional TVS diode with polarity indicated by a molded cathode band on the SMB (DO-214AA) package body. The banded end is the cathode and must be connected to ground or the lower-potential node; the opposite end is the anode and connects to the line being protected. No marking is present on bidirectional variants - a key visual differentiator.

What is the thermal resistance of SMBJ45A-M3/5B, and how does it affect layout?

SMBJ45A-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. To achieve rated 5.0 W power dissipation, PCB layout must provide these minimum pad dimensions and ensure adequate copper area for heat spreading. Reducing pad size increases R_θJA, derating both continuous and surge capability.