Alpha & Omega Semiconductor Inc. SMDJ30A

Overview

SMDJ30A from Alpha & Omega Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for high-energy ESD and surge protection in DC power lines and signal interfaces. It features a 30.0 V reverse stand-off voltage, 33.3–36.8 V breakdown voltage at 1 mA, 48.4 V maximum clamping voltage at 62.0 A peak pulse current, and 3000 W peak pulse power dissipation on a 10/1000 µs waveform - deployed in industrial motor drives to protect IGBT gate drivers from inductive switching transients.

For engineers reviewing the SMDJ30A datasheet, pinout, applications, or equivalent options, key selection criteria include unidirectional polarity, DO-214AB package compatibility, clamping performance under 10/1000 µs surges, thermal resistance (R_θJL = 15 °C/W), and compliance with JEDEC moisture sensitivity level MSL1.

Technical Context

The SMDJ30A operates as a silicon avalanche diode with glass-passivated junction, delivering fast response time (<1.0 ps from 0 V to V_BR) and low-profile DO-214AB packaging optimized for automated SMT assembly. Its unidirectional configuration provides cathode-anode conduction only during reverse overvoltage events, with a typical temperature coefficient of ΔV_BR = 0.1% × V_BR @ 25°C × ΔT.

Designed for non-repetitive surge suppression, it supports peak forward surge current (I_FSM) up to 300 A (8.3 ms half-sine), operates across –55 °C to +150 °C junction temperature range, and achieves 3000 W peak pulse power when mounted on 8.0 mm × 8.0 mm copper pads per terminal per JESD22-A114 test conditions.

Key Specifications

Pinout & Package

DO-214AB (SMC J-Bend) package: molded plastic case with matte tin lead-free plating, JEDEC-compliant outline, color band denoting cathode (positive end marking not applicable for unidirectional TVS).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SAC30A and 1.5SMC33A, the SMDJ30A delivers superior clamping precision (±5.3% VBR), lowest clamping voltage (48.4 V), and guaranteed 3000 W surge rating - making it optimal for high-reliability industrial and automotive power rail protection where voltage margin is constrained.

Availability

SMDJ30A is available at Aetrix Electronics and suitable for industrial motor drives, DC power input protection, and automotive body control modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant green packaging.

Supply support for SMDJ30A 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

Alpha & Omega Semiconductor (AOS) is a fabless power semiconductor company specializing in high-efficiency MOSFETs, TVS diodes, and power ICs for industrial, computing, and consumer markets.

The SMDJxxxA series is engineered for robust transient suppression in harsh environments, targeting applications demanding high peak power handling, low clamping voltage, and MSL1 reflow compatibility in surface-mount power systems.

FAQ

What is the breakdown voltage range of the SMDJ30A at 1 mA test current?

The SMDJ30A has a reverse breakdown voltage (V_BR) range of 33.3 V to 36.8 V at 1 mA test current, measured per JEDEC JESD22-A114. This narrow tolerance ensures consistent clamping behavior across production lots and supports precise overvoltage protection design in circuits where margin to IC absolute maximum ratings is critical. The SMDJ30A's specified V_BR directly enables reliable coordination with downstream voltage supervisors and regulators.

Is the SMDJ30A suitable for bidirectional surge protection?

No, the SMDJ30A is a unidirectional TVS diode, indicated by the "A" suffix and single cathode band marking. For bidirectional protection, the SMDJ30CA variant must be used - it provides symmetrical clamping in both polarities. Using the SMDJ30A in a bidirectional application would result in forward conduction and failure during negative transients. Always verify polarity marking and schematic symbol alignment before placing the SMDJ30A in circuit.

What is the maximum clamping voltage of the SMDJ30A and under what test condition?

The SMDJ30A has a maximum clamping voltage (V_C) of 48.4 V at 62.0 A peak pulse current, tested using the standardized 10/1000 µs double-exponential surge waveform. This value defines the upper voltage limit imposed on protected circuitry during worst-case transients and is measured with the device mounted on 8.0 mm × 8.0 mm copper pads per terminal. The SMDJ30A's 48.4 V clamping ensures safe operation of 3.3 V, 5 V, and 24 V logic and power ICs when properly coordinated.

Does the SMDJ30A meet moisture sensitivity level (MSL) requirements for lead-free reflow?

Yes, the SMDJ30A meets MSL Level 1 per J-STD-020, with a maximum lead-free reflow peak temperature of 260 °C. Its DO-214AB package uses matte tin lead-free plating and UL 94V-0 compliant molding compound, enabling compatibility with standard Pb-free reflow profiles without pre-bake. This makes the SMDJ30A suitable for high-volume automated assembly in industrial and automotive manufacturing where process consistency and yield are critical.

What is the thermal resistance from junction to lead (RθJL) for the SMDJ30A?

The SMDJ30A has a typical junction-to-lead thermal resistance (R_θJL) of 15 °C/W, measured under standard test conditions. This low value reflects efficient heat conduction from the silicon die through the internal leadframe to the PCB copper, supporting sustained power dissipation and improved reliability in thermally constrained layouts. When designing heatsinking for the SMDJ30A, R_θJL is the dominant thermal path - making copper pad size and thickness more impactful than ambient convection alone.