Vishay General Semiconductor - Diodes Division SMA5J18A-E3/61

Overview

SMA5J18A-E3/61 from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for high-energy surge protection on power and signal lines. It features a 18 V stand-off voltage (V_WM), 20.0–22.1 V breakdown voltage (V_BR), 29.2 V clamping voltage (V_C) at 17.1 A peak pulse current, and 500 W peak pulse power rating with 10/1000 µs waveform - used to protect MOSFETs, ICs, and sensor interfaces in automotive and industrial power supplies.

For engineers reviewing the SMA5J18A-E3/61 datasheet, SMA5J18A-E3/61 pinout, SMA5J18A-E3/61 application, or SMA5J18A-E3/61 equivalent, key selection criteria include unidirectional polarity, 150 °C max junction temperature, RoHS-compliant matte tin plating, MSL Level 1 moisture sensitivity, and compatibility with automated SMT placement on 5.0 mm × 5.0 mm copper pads.

Technical Context

This TVS diode operates as a voltage-clamping overvoltage protection device, triggered when reverse voltage exceeds its V_BR threshold. Its glass-passivated junction ensures stable breakdown behavior and low leakage (<1.0 µA at V_WM), while low incremental surge resistance enables effective energy diversion during transients induced by inductive load switching or ESD events.

The SMA5J18A-E3/61 is rated for non-repetitive 10/1000 µs surges up to 500 W and supports unidirectional forward surge current of 40 A (8.3 ms half-sine). Thermal resistance is 80 °C/W (junction-to-ambient) and 25 °C/W (junction-to-lead), requiring appropriate PCB copper area for thermal management under repeated stress conditions.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, UL 94 V-0 rated, MSL Level 1, 260 °C peak reflow temperature. Polarity indicated by cathode band at one end.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMA5J18A-E3/61, the M3 variant offers identical protection performance with halogen-free construction, while the CA variant enables symmetrical clamping for AC or differential applications - neither is pin-compatible in function unless polarity and signal topology match the original design intent.

Availability

SMA5J18A-E3/61 is available at Aetrix Electronics and suitable for automotive power rail protection, industrial sensor interface protection, and consumer power adapter input stage applications requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for SMA5J18A-E3/61 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 density, and automotive qualification.

The SMA5J series is engineered for high-power-density transient suppression in space-constrained, high-reliability environments - targeting automotive, industrial, and computing applications where robustness against ISO 7637, IEC 61000-4-5, and EFT threats is mandatory.

FAQ

What is the clamping voltage of the SMA5J18A-E3/61 under maximum surge conditions?

The SMA5J18A-E3/61 has a maximum clamping voltage (V_C) of 29.2 V at 17.1 A peak pulse current (I_PPM) using the standardized 10/1000 µs waveform. This value is measured per JEDEC test conditions and defines the upper voltage limit imposed on protected circuitry during a 500 W transient event. The SMA5J18A-E3/61 maintains this clamping performance across its specified operating temperature range.

Is the SMA5J18A-E3/61 suitable for automotive applications?

Yes, the SMA5J18A-E3/61 meets commercial-grade specifications and is part of a family where AEC-Q101 qualified variants exist (e.g., SMA5J18AHE3_A). While the E3/61 suffix itself is not AEC-Q101 certified, its construction - including glass-passivated junction, MSL Level 1 rating, and 150 °C T_J max - supports use in non-safety-critical automotive subsystems such as body electronics and infotainment power rails. Always verify qualification status per ordering code.

What does the "-E3/61" suffix indicate in SMA5J18A-E3/61?

The "-E3" suffix denotes RoHS-compliant, commercial-grade construction with matte tin-plated leads; "/61" specifies packaging in 7-inch diameter plastic tape and reel, with a base quantity of 1800 units. This format aligns with Vishay's standardized ordering nomenclature and ensures compatibility with high-volume SMT assembly lines. The SMA5J18A-E3/61 is not halogen-free - that variant uses the "-M3" suffix.

How does the SMA5J18A-E3/61 differ from the SMA5J18CA-E3/61?

The SMA5J18A-E3/61 is unidirectional with cathode-band polarity marking and conducts only in reverse avalanche; the SMA5J18CA-E3/61 is bidirectional, with symmetrical breakdown in both directions and no polarity marking. Both share identical V_BR, V_C, and P_PPM, but the CA version is required for AC-coupled or floating signal paths like RS-485 or CAN, whereas the A version suits DC power rails with defined ground reference.

What PCB layout guidance applies to the SMA5J18A-E3/61 for optimal thermal performance?

Vishay specifies mounting the SMA5J18A-E3/61 on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal to achieve rated 500 W pulse power. Minimizing trace length and maximizing copper area connected to both anode and cathode pads reduces thermal impedance and prevents localized overheating during repetitive surges. The SMA5J18A-E3/61's R_θJA of 80 °C/W assumes this layout; smaller pads increase junction temperature and reduce surge capability.