Alpha & Omega Semiconductor Inc. SMDJ17A

Overview

SMDJ17A from Alpha & Omega Semiconductor is a unidirectional transient voltage suppressor diode (TVS) designed for robust overvoltage protection in DC power rails and signal lines. It features a 17.0 V reverse standoff voltage (VRWM), 18.9–20.9 V breakdown voltage (VBR) at 1 mA, 27.6 V maximum clamping voltage at 108.7 A peak pulse current, and 3000 W peak pulse power dissipation on a 10/1000 µs waveform - deployed in industrial motor drives to safeguard IGBT gate drivers against inductive switching transients.

For engineers reviewing the SMDJ17A datasheet, pinout, applications, or equivalent options, key selection criteria include unidirectional polarity, DO-214AB package compatibility with high-current PCB layouts, clamping performance under repetitive surge conditions, and thermal resistance (R_θJL = 15 °C/W) for sustained operation near 150 °C junction temperature.

Technical Context

The SMDJ17A operates as a silicon avalanche diode with glass-passivated junction, enabling fast response (<1.0 ps) and stable breakdown characteristics. Its unidirectional configuration provides cathode-anode conduction only during reverse overvoltage events, with a color band marking the cathode terminal per JEDEC DO-214AB mechanical standard.

Designed for surface-mount use on 8.0 mm × 8.0 mm copper pads, it delivers 3000 W peak pulse power handling and supports ≤0.01% duty cycle repetition. Thermal performance is defined by R_θJL = 15 °C/W and R_θJA = 75 °C/W, with operating junction temperature spanning –55 °C to +150 °C.

Key Specifications

Pinout & Package

Package: DO-214AB (SMC J-Bend), molded plastic case with matte tin lead-free plating, MSL Level 1, JEDEC-compliant, 8.0 mm × 8.0 mm copper pad mounting requirement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SAC17 and SMLJ17A, the SMDJ17A delivers double the peak pulse power (3000 W vs. 1500 W), lower thermal resistance (R_θJL = 15 °C/W), and surface-mount scalability - making it the preferred choice for high-reliability, high-energy industrial and automotive surge protection where board space and thermal performance are critical.

Availability

SMDJ17A is available at Aetrix Electronics and suitable for industrial motor drives, automotive power distribution units, and renewable energy inverters requiring stable component supply, RoHS-compliant packaging, and traceable sourcing for long-lifecycle programs.

Supply support for SMDJ17A 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 automotive markets.

The SMDJ series is part of AOS's high-power TVS portfolio, engineered specifically for robust transient suppression in harsh environments - emphasizing high PPPM, low clamping ratio, and JEDEC-qualified surface-mount reliability.

FAQ

What is the clamping voltage of the SMDJ17A under maximum rated surge current?

The SMDJ17A has a maximum clamping voltage (V_C) of 27.6 V when subjected to its rated peak pulse current (I_PPM) of 108.7 A on a 10/1000 µs waveform. This value is measured per industry-standard test conditions and defines the upper voltage limit imposed on protected circuitry during a full-rated transient event. The SMDJ17A maintains this clamping performance consistently due to its glass-passivated avalanche junction and low dynamic impedance.

Is the SMDJ17A suitable for bidirectional transient protection?

No, the SMDJ17A is a unidirectional TVS diode, intended only for circuits with defined DC polarity such as positive-ground or negative-ground power rails. For bidirectional protection, the SMDJ17CA variant must be used - it shares identical voltage ratings but conducts symmetrically in both directions. The SMDJ17A's cathode band marks the terminal that must be connected toward the protected line, and it will not clamp positive transients on anode-referenced nodes.

What is the thermal resistance specification for the SMDJ17A, and how does it affect PCB layout?

The SMDJ17A has a typical junction-to-lead thermal resistance (R_θJL) of 15 °C/W and junction-to-ambient (R_θJA) of 75 °C/W when mounted on 8.0 mm × 8.0 mm copper pads per terminal. To achieve rated 3000 W pulse handling and avoid thermal runaway, PCB layout must allocate minimum 64 mm² copper area per terminal with direct thermal vias to inner ground/power planes. The SMDJ17A's low R_θJL enables efficient heat transfer into the PCB, but insufficient copper reduces effective power rating significantly.

Does the SMDJ17A meet automotive qualification standards?

The SMDJ17A is AEC-Q200 stress-tested and compliant with ISO 7637-2 Pulse 5a (load dump) requirements when applied per manufacturer guidelines - including proper PCB copper sizing and thermal management. While not AEC-Q101 qualified as a discrete diode, its 150 °C TJ max, 3000 W PPPM, and UL 94V-0 housing make it widely adopted in automotive power distribution modules. Always verify system-level surge testing with the exact SMDJ17A implementation in your design.

What is the reverse leakage current of the SMDJ17A at its rated standoff voltage?

The SMDJ17A exhibits a maximum reverse leakage current (I_R) of 2.0 µA at its rated reverse standoff voltage (V_RWM) of 17.0 V and ambient temperature of 25 °C. This ultra-low leakage ensures minimal power loss in always-on protection configurations and avoids unintended loading of high-impedance sensor or reference circuits. The SMDJ17A maintains this specification across its full operating temperature range (–55 °C to +150 °C), with leakage increasing predictably per its specified temperature coefficient.