Vishay General Semiconductor - Diodes Division SMBG78CA-M3/52

Overview

SMBG78CA-M3/52 from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMBG (DO-215AA) package, designed for clamping voltage transients on signal or power lines. It features a 78 V stand-off voltage (V_WM), 86.7–95.8 V breakdown voltage (V_BR) at 1 mA, 126 V maximum clamping voltage (V_C) at 4.8 A peak pulse current, and 600 W peak pulse power rating with 10/1000 μs waveform - used to protect automotive sensor interfaces and industrial I/O circuits against ESD and load dump.

For engineers reviewing the SMBG78CA-M3/52 datasheet, SMBG78CA-M3/52 pinout, SMBG78CA-M3/52 application, or SMBG78CA-M3/52 equivalent, key selection criteria include bidirectional clamping capability, AEC-Q101 qualification, halogen-free RoHS compliance (M3 suffix), low incremental surge resistance, and compatibility with automated SMT placement on 5.0 mm × 5.0 mm copper pads.

Technical Context

This device operates as a voltage-clamped crowbar during transient events, leveraging an avalanche breakdown mechanism across both polarities. Its bidirectional symmetry ensures identical clamping behavior for positive and negative surges, with no polarity marking required on the SMBG package.

Thermal performance is defined by R_θJA = 100 °C/W (typ.) and R_θJL = 20 °C/W (typ.), enabling reliable operation up to T_J = +150 °C. It meets J-STD-020 MSL Level 1 and withstands 8.3 ms half-sine surge currents up to 100 A in unidirectional variants - though SMBG78CA-M3/52 is bidirectional and thus excludes IFSM rating.

Key Specifications

Pinout & Package

SMBG78CA-M3/52 uses a 2-terminal SMBG (DO-215AA) package with gull-wing leads. No polarity marking is applied, as the device is symmetrically bidirectional - both terminals function identically as either anode or cathode depending on transient polarity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBG78CA-M3/52, SMBG78CA-E3/52 lacks halogen-free certification and AEC-Q101 validation, while SMBG78CAHM3/52 provides identical performance plus formal automotive qualification - making it suitable for ASIL-B environments where traceability and reliability evidence are mandatory.

Availability

SMBG78CA-M3/52 is available at Aetrix Electronics and suitable for automotive electronics, industrial sensor interfaces, and 12 V power rail protection requiring stable component supply across multi-year production cycles.

Supply support for SMBG78CA-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, TVS devices, and optoelectronics with emphasis on reliability and automotive-grade validation.

The SMBG series was engineered specifically for surface-mount transient suppression in harsh environments - targeting automotive, industrial, and telecom applications demanding AEC-Q101 compliance and high-energy surge resilience.

FAQ

What is the clamping voltage of SMBG78CA-M3/52 at its rated peak pulse current?

The SMBG78CA-M3/52 has a maximum clamping voltage (V_C) of 126 V at 4.8 A peak pulse current (I_PPM) under a 10/1000 μs waveform. This value is measured per Figure 1 in Vishay document 88456 and defines the upper voltage limit imposed on protected circuitry during surge events. The SMBG78CA-M3/52 maintains this clamping performance across its full operating temperature range (−55 °C to +150 °C) when mounted on 5.0 mm × 5.0 mm copper pads.

Is SMBG78CA-M3/52 suitable for automotive applications?

Yes, SMBG78CA-M3/52 is AEC-Q101 qualified and explicitly rated for automotive use, including under-hood environments. Its −55 °C to +150 °C junction temperature range, MSL Level 1 moisture sensitivity, and validation against mechanical shock, temperature cycling, and humidity testing meet Tier 1 OEM requirements. The SMBG78CA-M3/52 is commonly deployed in CAN/LIN bus protection, body control modules, and power supply rails in vehicles certified to ISO 16750 and ISO 7637 standards.

What does the "M3" suffix indicate in SMBG78CA-M3/52?

The "M3" suffix in SMBG78CA-M3/52 denotes halogen-free, RoHS-compliant construction meeting IPC-JEDEC J-STD-20 and JESD201 Class 2 whisker resistance requirements. It distinguishes the part from E3 (RoHS only) and HM3 (AEC-Q101 + halogen-free) variants. The SMBG78CA-M3/52 is intended for industrial and automotive applications where halogen-free materials are mandated by environmental policy or regulatory compliance programs.

How does SMBG78CA-M3/52 differ from unidirectional variants like SMBG78A-M3/52?

SMBG78CA-M3/52 is bidirectional with symmetrical clamping in both polarities and no cathode marking, whereas SMBG78A-M3/52 is unidirectional with a cathode band and specified IFSM = 100 A. The SMBG78CA-M3/52 has identical V_WM, V_BR, and V_C ratings but omits forward surge rating since it conducts equally in either direction. This makes SMBG78CA-M3/52 ideal for AC-coupled or differential lines like CAN, while SMBG78A-M3/52 suits DC power rails with defined polarity.

What is the thermal resistance of SMBG78CA-M3/52, and how does it affect layout design?

SMBG78CA-M3/52 has a typical junction-to-ambient thermal resistance (R_θJA) of 100 °C/W and junction-to-lead (R_θJL) of 20 °C/W when mounted on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. To maintain T_J ≤ 150 °C under repetitive 600 W pulses, PCB layout must provide adequate copper area and minimize trace length. The SMBG78CA-M3/52 requires no thermal vias for single-pulse events but benefits from internal ground planes for sustained duty cycles above 0.01%.