Vishay General Semiconductor - Diodes Division SMAJ8.5A-E3/5A

Overview

SMAJ8.5A-E3/5A from Vishay General Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed to protect sensitive electronics against voltage transients induced by inductive load switching and lightning surges. It features a 8.5 V stand-off voltage (V_WM), 9.44–10.4 V breakdown voltage (V_BR) at 1 mA test current, and clamps up to 14.4 V at 27.8 A peak pulse current (I_PPM) under 10/1000 μs waveform - used for safeguarding MOSFETs, ICs, and sensor signal lines in automotive and industrial power supplies.

For engineers reviewing the SMAJ8.5A-E3/5A datasheet, SMAJ8.5A-E3/5A pinout, SMAJ8.5A-E3/5A application, or SMAJ8.5A-E3/5A equivalent, this device delivers verified 400 W peak pulse power capability, low incremental surge resistance, and AEC-Q101 qualification readiness (via HE3/HM3 variants), making it suitable for high-reliability board-level ESD and surge protection where fast response time (<1 ns) and stable clamping performance are critical.

Technical Context

This TVS diode operates as a unidirectional clamping device with cathode-banded polarity, leveraging a glass-passivated silicon junction to achieve sub-nanosecond response to transient overvoltages. Its thermal design relies on low R_θJA (120 °C/W) and R_θJL (30 °C/W), enabling effective power dissipation when mounted on 5.0 mm × 5.0 mm copper pads per terminal.

The SMAJ8.5A-E3/5A complies with ANSI/IEEE C62.35 standards for transient suppressors and meets J-STD-020 MSL Level 1 moisture sensitivity with 260 °C lead-free reflow peak. It supports repetitive surge duty cycles up to 0.01 % and maintains stable clamping across -55 °C to +150 °C operating junction temperature range.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, low-profile plastic case with matte tin-plated leads solderable per J-STD-002 and JESD 22-B102. Polarity indicated by cathode band on one end.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ8.5A-E3/5A, the M3 variant adds halogen-free construction without altering surge performance, while the HE3 variant extends qualification to automotive reliability standards - both retain identical pinout, footprint, and clamping behavior but serve distinct compliance-driven use cases.

Availability

SMAJ8.5A-E3/5A is available at Aetrix Electronics and suitable for automotive power rail protection, industrial sensor interface hardening, and consumer adapter secondary-side surge suppression requiring stable component supply and full traceability.

Supply support for SMAJ8.5A-E3/5A 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, and protection devices with emphasis on reliability, efficiency, and application-specific optimization.

The SMAJ series was developed for high-energy transient suppression in space-constrained surface-mount applications, targeting automotive, industrial, and telecom systems where robustness and repeatable clamping are non-negotiable.

FAQ

What is the maximum clamping voltage of the SMAJ8.5A-E3/5A under a 10/1000 μs surge?

The SMAJ8.5A-E3/5A clamps to a maximum of 14.4 V when subjected to its rated peak pulse current of 27.8 A under the standardized 10/1000 μs waveform. This value is measured per ANSI/IEEE C62.35 and confirmed in Vishay's Document Number 88390, ensuring predictable overvoltage limiting for downstream ICs and MOSFETs in real-world surge events.

Is the SMAJ8.5A-E3/5A suitable for automotive applications?

The SMAJ8.5A-E3/5A itself is commercial-grade and RoHS-compliant, but Vishay offers the pin-identical SMAJ8.5AHE3_A/I variant that is fully AEC-Q101 qualified. For automotive use, engineers should specify the HE3 or HM3 suffix versions - the SMAJ8.5A-E3/5A serves as the baseline design reference and shares identical electrical characteristics, thermal behavior, and SMA (DO-214AC) footprint.

What does the "E3/5A" suffix indicate in SMAJ8.5A-E3/5A?

The "E3" denotes RoHS-compliant, commercial-grade construction with matte tin-plated leads, while "/5A" specifies packaging in 13-inch diameter plastic tape and reel containing 7500 units. This ordering code aligns with Vishay's preferred package format for high-volume SMT assembly and ensures compatibility with standard pick-and-place equipment feeders.

How does the SMAJ8.5A-E3/5A compare to SMAJ8.0A and SMAJ9.0A in terms of stand-off voltage?

The SMAJ8.5A-E3/5A has a V_WM of 8.5 V, positioned between SMAJ8.0A (8.0 V) and SMAJ9.0A (9.0 V). Its 9.44–10.4 V V_BR range provides tighter margin over V_WM than SMAJ8.0A (8.89–9.83 V) and slightly lower clamping (14.4 V vs. 15.4 V for SMAJ9.0A), making SMAJ8.5A-E3/5A optimal for 12 V systems where headroom and clamping trade-offs must be balanced precisely.

Does the SMAJ8.5A-E3/5A require heatsinking for standard operation?

No external heatsink is required for the SMAJ8.5A-E3/5A under typical single-event surge conditions, as its 400 W peak pulse rating is validated with 5.0 mm × 5.0 mm copper pads per terminal - standard for most 2-layer and 4-layer PCBs. Continuous power dissipation is limited to 3.3 W (P_D), so sustained overvoltage conditions demand careful thermal layout, but transient suppression remains effective without added thermal mass.