Alpha & Omega Semiconductor Inc. SMDJ75A

Overview

SMDJ75A from Alpha & Omega Semiconductor is a unidirectional transient voltage suppressor diode designed for high-energy surge protection in DC power lines and signal interfaces. It features a 75 V reverse stand-off voltage (VRWM), 83.3–92.1 V breakdown voltage (VBR) at 1 mA, 121 V maximum clamping voltage at 24.8 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 SMDJ75A datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin relative to protected IC VDD rails, thermal resistance (R_θJL = 15 °C/W), unidirectional polarity confirmation, and DO-214AB package compatibility with automated SMT placement and reflow profiles up to 260 °C.

Technical Context

The SMDJ75A operates as a silicon avalanche diode with glass-passivated junction, delivering sub-nanosecond response (<1.0 ps from 0 V to V_BR) and low dynamic impedance under transient stress. Its unidirectional configuration requires cathode-band orientation toward positive rail, enabling precise overvoltage clamping without reverse conduction during normal operation.

Thermally, it supports continuous operation from –55 °C to +150 °C junction temperature, with R_θJA = 75 °C/W (on 8 mm × 8 mm copper pads) and R_θJL = 15 °C/W - enabling reliable derating above 25 °C ambient per the published pulse derating curve. Repetition rate is limited to 0.01% duty cycle per JEDEC standards.

Key Specifications

Pinout & Package

Package: DO-214AB (SMC J-Bend), surface-mount molded plastic case with matte tin lead-free plating, MSL Level 1 (260 °C peak reflow), UL 94V-0 flammability rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ75A and 1.5KE75A, the SMDJ75A uniquely delivers 3000 W surge capability in a compact, lead-free, RoHS-compliant DO-214AB package optimized for high-volume SMT manufacturing - making it the preferred choice for industrial-grade DC bus protection where energy handling and assembly scalability are critical.

Availability

SMDJ75A is available at Aetrix Electronics and suitable for industrial motor drives, telecom power feeds, and automotive body control modules requiring stable component supply, long-term lifecycle assurance, and full traceability under AEC-Q200-aligned quality controls.

Supply support for SMDJ75A 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 SMDJ series is part of AOS's transient voltage suppressor portfolio, engineered specifically for high-power, surface-mount surge protection in harsh-environment applications demanding reliability, low clamping voltage, and MSL1 reflow compatibility.

FAQ

What is the maximum clamping voltage of the SMDJ75A under a 10/1000 µs surge?

The SMDJ75A exhibits a maximum clamping voltage (V_C) of 121 V when subjected to its rated peak pulse current of 24.8 A on a 10/1000 µs waveform. This value is measured per JEDEC standards and defines the upper voltage limit imposed on protected circuitry during transient events - critical for ensuring downstream components remain within their absolute maximum ratings. The SMDJ75A maintains this performance across its full operating temperature range.

Is the SMDJ75A suitable for bidirectional surge protection?

No, the SMDJ75A is a unidirectional transient voltage suppressor. Its cathode band denotes polarity, and it conducts only when the cathode is at a higher potential than the anode. For bidirectional protection, the SMDJ75CA variant must be used - which has symmetrical breakdown in both directions and no polarity marking. Using SMDJ75A in a bidirectional configuration risks failure during negative transients.

What is the thermal resistance from junction to lead (RθJL) for the SMDJ75A?

The SMDJ75A has a typical junction-to-lead thermal resistance (R_θJL) of 15 °C/W, measured under standard test conditions. This low value enables efficient heat transfer from the silicon die to the PCB copper via the leads, supporting repeated surge events without thermal runaway. Designers should ensure adequate copper area (minimum 8 mm × 8 mm per terminal) to realize this spec in practice - directly impacting SMDJ75A reliability in high-duty-cycle applications.

Does the SMDJ75A meet RoHS and halogen-free requirements?

Yes, the SMDJ75A is an AOS Green Product: fully RoHS compliant (2011/65/EU), lead-free, and halogen-free per IEC 61249-2-21. It carries matte tin plating and meets UL 94V-0 flammability rating. These attributes are verified in AOS' official compliance documentation and support global environmental regulations - essential for export-controlled industrial and automotive programs requiring full material declarations.

What is the reverse leakage current (IR) of the SMDJ75A at its VRWM voltage?

At its rated reverse stand-off voltage (VRWM) of 75 V, the SMDJ75A exhibits a maximum reverse leakage current (I_R) of 2.0 µA at 25 °C. This ultra-low leakage minimizes standby power loss in always-on systems such as telecom power feeds or automotive ECUs. Leakage remains below 10 µA even at +125 °C, ensuring stable operation across the full industrial temperature range without compromising system efficiency.