Vishay General Semiconductor - Diodes Division SMAJ30CAHE3_A/H

Overview

SMAJ30CAHE3_A/H from Vishay General Semiconductor is a bidirectional surface-mount Transient Voltage Suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping voltage transients on signal or power lines. It features a 30 V standoff voltage (VWM), 48.4 V maximum clamping voltage at 8.3 A peak pulse current (IPPM), and 400 W peak pulse power rating with 10/1000 μs waveform - used to protect MOSFETs, ICs, and sensor signal lines in automotive and industrial control systems.

For engineers reviewing the SMAJ30CAHE3_A/H datasheet, SMAJ30CAHE3_A/H pinout, SMAJ30CAHE3_A/H application, or SMAJ30CAHE3_A/H equivalent, key selection criteria include bidirectional clamping capability, AEC-Q101 qualification, low incremental surge resistance, and compatibility with automated SMT assembly on 0.2" × 0.2" copper pads.

Technical Context

This TVS diode operates symmetrically in both directions due to its bidirectional CA construction, enabling protection of AC-coupled or differential signal paths without polarity concerns. Its glass-passivated junction ensures stable breakdown behavior and fast response (<1 ns) to ESD and lightning-induced surges.

The device is rated for 400 W peak pulse power (derated to 300 W above 78 V), with thermal resistance R_θJA = 120 °C/W and R_θJL = 30 °C/W, supporting operation from –55 °C to +150 °C junction temperature. It meets MSL Level 1 per J-STD-020 and is qualified to AEC-Q101 for automotive use.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, low-profile case with matte tin-plated leads solderable per J-STD-002. No polarity marking for bidirectional types.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ30CA-M3, the SMAJ30CAHE3_A/H adds AEC-Q101 qualification and identical RoHS compliance, making it mandatory for automotive designs; versus SMBJ30CAHE3_A/H, it trades 200 W lower pulse power for smaller SMA footprint and tighter board area utilization.

Availability

SMAJ30CAHE3_A/H is available at Aetrix Electronics and suitable for automotive ECUs, industrial PLC I/O modules, consumer USB-C power delivery circuits, and telecom line card designs requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for SMAJ30CAHE3_A/H 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, efficiency, and application-specific optimization.

The SMAJ series is engineered for robust transient suppression in harsh environments - targeting automotive, industrial, and telecom applications where failure tolerance and long-term stability are critical.

FAQ

What is the clamping voltage of SMAJ30CAHE3_A/H at its rated peak pulse current?

The SMAJ30CAHE3_A/H has a maximum clamping voltage (V_C) of 48.4 V at 8.3 A peak pulse current (I_PPM) under the standard 10/1000 μs waveform. This value is measured per Figure 1 and Table on page 2 of Vishay document 88390, and defines the upper voltage limit imposed on protected circuitry during surge events. The SMAJ30CAHE3_A/H maintains this clamping performance across its full operating temperature range.

Is SMAJ30CAHE3_A/H suitable for automotive applications?

Yes, SMAJ30CAHE3_A/H is AEC-Q101 qualified, as confirmed by the "HE3" suffix in its ordering code and footnote (1) on page 3 of Vishay document 88390. It undergoes stress testing for high-temperature operating life, temperature cycling, and ESD immunity required for automotive electronics. The SMAJ30CAHE3_A/H is commonly deployed in body control units, infotainment power supplies, and ADAS sensor interfaces.

What is the standoff voltage (V_WM) and why does it matter for SMAJ30CAHE3_A/H?

The standoff voltage (V_WM) of SMAJ30CAHE3_A/H is 30 V - the maximum DC or continuous reverse voltage the device tolerates without entering avalanche conduction. This parameter ensures the SMAJ30CAHE3_A/H remains non-conductive during normal operation while allowing sufficient margin below its 33.3 V minimum breakdown voltage (V_BR). Selecting V_WM ≥ 1.1× nominal line voltage prevents leakage and power loss in applications like 24 V industrial controls or 12 V automotive systems.

Does SMAJ30CAHE3_A/H have polarity markings on the package?

No, SMAJ30CAHE3_A/H does not feature polarity markings because it is a bidirectional TVS diode (denoted by the "CA" suffix). As stated in the "Mechanical Data" section of Vishay document 88390, "no marking on bidirectional types." Both terminals are functionally identical, allowing placement in either orientation on the PCB - simplifying layout and eliminating orientation-related assembly errors.

What is the thermal resistance of SMAJ30CAHE3_A/H and how does it affect PCB layout?

The SMAJ30CAHE3_A/H has a typical junction-to-ambient thermal resistance (R_θJA) of 120 °C/W and junction-to-lead (R_θJL) of 30 °C/W, per page 3 of Vishay document 88390. These values assume mounting 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 allocate adequate copper area and avoid excessive trace length - the SMAJ30CAHE3_A/H relies on PCB copper for heat dissipation, not an external heatsink.