Vishay General Semiconductor - Diodes Division SMAJ550HM3_B/H

Overview

SMAJ550HM3_B/H from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode in SMA (DO-214AC) package, rated for 550 V breakdown voltage (V_BR), 495 V working voltage (V_WM), 760 V clamping voltage at 400 mA, 300 W peak pulse power (10/1000 µs), and AEC-Q101 qualified for automotive use - deployed to protect MOSFETs and sensor signal lines against inductive switching transients.

For engineers reviewing the SMAJ550HM3_B/H datasheet, SMAJ550HM3_B/H pinout, SMAJ550HM3_B/H application, or SMAJ550HM3_B/H equivalent, key selection criteria include verified unidirectional polarity, clamping performance under 400 mA 10/1000 µs surge, thermal resistance (R_θJL = 30 °C/W), AEC-Q101 qualification status, and compatibility with standard SMA PCB pad layouts per J-STD-020 MSL level 1.

Technical Context

This TVS diode operates exclusively in unidirectional mode, with cathode marked by a band and designed for reverse-biased transient clamping. Its 550 V V_BR (min) and 495 V V_WM enable robust standoff in high-voltage DC rails, while the 760 V V_C at 400 mA ensures predictable overvoltage limiting during ESD or load-dump events.

Thermal design relies on R_θJL = 30 °C/W and R_θJA = 120 °C/W (on minimum pad layout), supporting operation up to T_J = 150 °C. The device exhibits 90 pF capacitance at 0 V and 7.5 pF at 200 V, making it suitable for moderate-speed signal line protection without excessive loading.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, halogen-free, RoHS-compliant, AEC-Q101 qualified. Cathode indicated by molded band; leads matte tin-plated, solderable per J-STD-002.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ550HM3_B/H, SMAJ550A-M3/61 offers identical electrical specs without automotive qualification, while SMCJ550A-HM3 delivers higher surge capacity in a physically larger package - neither is pin-compatible, and both require explicit validation for thermal and layout integration.

Availability

SMAJ550HM3_B/H is available at Aetrix Electronics and suitable for automotive power distribution, industrial motor drives, telecom interface protection, and consumer sensor systems requiring stable component supply with full traceability and AEC-Q101 compliance.

Supply support for SMAJ550HM3_B/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, thermal performance, and automotive-grade qualification.

The SMAJ series is engineered specifically for high-voltage transient suppression in space-constrained, thermally demanding applications - targeting automotive subsystems, industrial controls, and infrastructure equipment where AEC-Q101 compliance and repeatable clamping behavior are mandatory.

FAQ

What is the clamping voltage of SMAJ550HM3_B/H and under what test condition is it specified?

The SMAJ550HM3_B/H has a maximum clamping voltage (V_C) of 760 V, measured at 400 mA peak pulse current using the standardized 10/1000 µs double-exponential waveform. This value defines the upper voltage limit imposed on protected circuitry during transient events and is validated per JEDEC standards. The SMAJ550HM3_B/H maintains this clamping performance across its qualified operating temperature range.

Is SMAJ550HM3_B/H suitable for automotive applications, and what qualification does it hold?

Yes, SMAJ550HM3_B/H is explicitly AEC-Q101 qualified, as confirmed by Vishay's ordering code suffix "HM3" and documentation revision 09-Jan-2024. It meets stress testing requirements for temperature cycling, humidity bias, and mechanical shock applicable to automotive powertrain and body electronics. The SMAJ550HM3_B/H is intended for production use in Tier-1 and Tier-2 automotive systems where long-term reliability under harsh conditions is required.

What is the package type and mounting specification for SMAJ550HM3_B/H?

SMAJ550HM3_B/H uses the SMA (DO-214AC) surface-mount package with matte tin-plated leads compliant with J-STD-002 and JESD 22-B102. It is rated MSL Level 1 (260 °C peak reflow), requires no moisture preconditioning, and mounts on 0.2" × 0.2" copper pads per terminal for thermal performance. The cathode is marked by a visible band, and polarity must be observed during placement to ensure correct unidirectional clamping function.

How does the thermal resistance of SMAJ550HM3_B/H affect its power handling capability?

SMAJ550HM3_B/H has a typical junction-to-lead thermal resistance (R_θJL) of 30 °C/W and junction-to-ambient (R_θJA) of 120 °C/W on minimum recommended pads. These values directly determine safe operating area: at 25 °C ambient, the 2.5 W steady-state power dissipation (P_D) is limited by R_θJA, while pulsed operation leverages R_θJL for short-duration energy absorption. Derating curves in the datasheet must be applied above 25 °C to maintain T_J ≤ 150 °C.

What is the capacitance profile of SMAJ550HM3_B/H, and how does it impact signal line protection?

SMAJ550HM3_B/H exhibits 90 pF capacitance at 0 V bias and drops to 7.5 pF at 200 V, reflecting its voltage-dependent junction behavior. This low, bias-sensitive capacitance minimizes loading on high-impedance analog or digital signal lines - such as sensor outputs or communication buses - preserving signal rise/fall times and reducing crosstalk risk. For SMAJ550HM3_B/H, this makes it appropriate for protecting lines up to ~10 MHz without significant bandwidth degradation.