Vishay General Semiconductor - Diodes Division SMBJ15A-M3/52

Overview

SMBJ15A-M3/52 from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode in SMB (DO-214AA) package, designed for clamping voltage transients on power and signal lines. It features a 15 V stand-off voltage (V_WM), 16.7–18.5 V breakdown voltage (V_BR) at 1 mA, 24.4 V maximum clamping voltage (V_C) at 24.6 A peak pulse current, and 600 W peak pulse power rating with 10/1000 µs waveform - used to protect MOSFETs, ICs, and sensor interfaces in industrial power supplies and telecom line cards.

For engineers reviewing the SMBJ15A-M3/52 datasheet, SMBJ15A-M3/52 pinout, SMBJ15A-M3/52 application, or SMBJ15A-M3/52 equivalent, key selection criteria include unidirectional polarity, 1.0 µA max reverse leakage at 15 V, 150 °C max junction temperature, 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 clamping device in parallel with sensitive circuitry, conducting only when transient voltage exceeds its breakdown threshold. Its glass-passivated junction ensures stable avalanche behavior, low incremental surge resistance (enabling tight clamping), and fast response time (<1 ps) to sub-microsecond transients induced by inductive switching or ESD events.

The SMBJ15A-M3/52 is rated for non-repetitive 10/1000 µs surges up to 24.6 A, with thermal resistance of 100 °C/W (junction-to-ambient) and 20 °C/W (junction-to-lead). It meets MSL Level 1 per J-STD-020 and supports lead-free reflow profiles with peak temperature up to 260 °C.

Key Specifications

Pinout & Package

Package: SMB (DO-214AA), surface-mount, halogen-free, RoHS-compliant, matte tin-plated leads. Cathode indicated by band marking on cathode end.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ15A-E3/52, the M3/52 offers halogen-free compliance critical for automotive and green electronics programs; versus SMBJ15CA-M3/52, it provides lower leakage and polarity-specific clamping essential for DC power and unidirectional digital lines.

Availability

SMBJ15A-M3/52 is available at Aetrix Electronics and suitable for industrial motor drives, telecom line cards, and consumer appliance power supplies requiring stable component supply, halogen-free compliance, and repeatable surge performance.

Supply support for SMBJ15A-M3/52 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 industrial automation, telecom infrastructure, and automotive electronics where robustness and long-term stability are mandatory.

FAQ

What is the maximum clamping voltage of SMBJ15A-M3/52 under a 10/1000 µs surge?

The SMBJ15A-M3/52 has a maximum clamping voltage (V_C) of 24.4 V when subjected to its rated peak pulse current of 24.6 A with a 10/1000 µs waveform. This value is measured per ANSI/IEEE C62.35 and reflects the actual voltage imposed on protected circuitry during worst-case transient events. The SMBJ15A-M3/52 maintains this clamping performance across its full operating temperature range of –55 °C to +150 °C.

Is SMBJ15A-M3/52 suitable for automotive applications?

The SMBJ15A-M3/52 itself is commercial-grade and not AEC-Q101 qualified; however, Vishay offers the functionally identical SMBJ15A-HM3_X variant (e.g., SMBJ15A-HM3_A) which carries AEC-Q101 qualification. For automotive body control modules or infotainment systems requiring automotive-grade TVS diodes, the HM3_X version must be specified. The SMBJ15A-M3/52 remains appropriate for non-automotive industrial and telecom uses where halogen-free RoHS compliance is required.

What does the "M3" suffix indicate in SMBJ15A-M3/52?

The "M3" suffix in SMBJ15A-M3/52 denotes halogen-free, RoHS-compliant construction meeting IEC 61249-2-21 requirements, with no brominated or chlorinated flame retardants in the molding compound. It also signifies compliance with JESD201 Class 2 whisker resistance and matte tin plating per J-STD-002. This distinguishes it from the E3 suffix (RoHS-compliant but not halogen-free) and HE3/HM3 variants (AEC-Q101 qualified).

How does SMBJ15A-M3/52 differ from SMBJ15CA-M3/52?

The SMBJ15A-M3/52 is unidirectional with cathode marking and 1.0 µA max reverse leakage at 15 V, optimized for DC power rails and unidirectional signal lines. In contrast, SMBJ15CA-M3/52 is bidirectional - symmetrical in both directions, no polarity marking, and 2.0 µA max leakage - intended for AC-coupled or floating interfaces like RS-485 or audio. Both share identical V_BR, V_C, and P_PPM, but their circuit roles and layout requirements differ fundamentally.

What is the thermal resistance of SMBJ15A-M3/52, and how does it affect PCB layout?

The SMBJ15A-M3/52 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 maintain safe junction temperatures under repetitive surge conditions, designers must provide adequate copper area and avoid excessive trace length between the device and ground plane. Reducing pad size or using thin FR-4 increases R_θJA, potentially limiting surge duty cycle or requiring derating per Figure 2 in the Vishay datasheet 88392.