Taiwan Semiconductor Corporation 5.0SMDJ18A

Overview

5.0SMDJ18A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for high-energy surge protection in DC power lines and I/O interfaces. It delivers 5000W peak pulse power at 10/1000μs, clamps transients to 29.2V at 172A, and features a 20.0–22.1V breakdown voltage with <1.0ps response time. Used in AC/DC power supplies and industrial I/O protection circuits.

For engineers reviewing the 5.0SMDJ18A datasheet, 5.0SMDJ18A pinout, 5.0SMDJ18A application, or 5.0SMDJ18A equivalent, key selection criteria include its DO-214AB (SMC) package, 18V working standoff voltage, 29.2V max clamping voltage at 172A, ±0.098 mV/°C V_BR temperature coefficient, and JESD201 Class 2 whisker resistance.

Technical Context

The 5.0SMDJ18A employs a stacked-die construction in a unidirectional configuration, enabling robust clamping performance under repetitive surge stress. Its photo-glass passivated junction ensures stable leakage (<10µA at 18V) and long-term reliability across -55°C to +175°C operating range.

Thermal design is supported by R_θJL = 16°C/W and R_θJA = 61°C/W (on 16mm × 16mm Cu pad), allowing effective heat dissipation during 5000W transient events. The device meets J-STD-020 moisture sensitivity level 1 and RoHS/halogen-free compliance per IEC 61249-2-21.

Key Specifications

Pinout & Package

Package: DO-214AB (SMC), surface-mount, polarity indicated by cathode band. Matte tin-plated leads, solderable per J-STD-002; UL 94V-0 molding compound.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ18A and SMCJ18A, the 5.0SMDJ18A offers identical clamping performance and surge rating to SMCJ18A but exceeds SMBJ18A by >8× peak power, making it essential for high-threat industrial power and interface protection where sustained 5kW transients occur.

Availability

5.0SMDJ18A is available at Aetrix Electronics and suitable for AC/DC power supply protection, industrial I/O interface hardening, and motor drive control board surge suppression requiring stable component supply and long-term lifecycle support.

Supply support for 5.0SMDJ18A 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated Taiwanese semiconductor manufacturer specializing in discrete power devices, TVS diodes, and rectifiers since 1979.

The 5.0SMDJ18A belongs to TSC's high-power SMDJ series, engineered specifically for industrial-grade transient suppression where 5000W surge handling, extended temperature operation, and automated assembly compatibility are mandatory.

FAQ

What is the maximum clamping voltage of the 5.0SMDJ18A under full-rated surge current?

The 5.0SMDJ18A exhibits a maximum clamping voltage (V_C) of 29.2 V when subjected to its rated peak pulse current of 172 A at the 10/1000μs waveform. This value is measured per standard test conditions (T_A = 25°C) and defines the upper voltage limit imposed on protected circuitry during worst-case surge events. Designers use this parameter to verify that downstream components remain within their absolute maximum ratings.

Is the 5.0SMDJ18A unidirectional or bidirectional, and how is polarity identified?

5.0SMDJ18A is a unidirectional TVS diode, intended for suppressing positive-going transients only. Polarity is marked by a distinct cathode band on the DO-214AB (SMC) package body. During PCB layout, the cathode must be connected to the line being protected (e.g., +24V rail), and the anode to reference ground - reversal prevents proper clamping operation and may cause catastrophic failure.

What is the working standoff voltage (V_WM) of the 5.0SMDJ18A, and why is it critical for system design?

The 5.0SMDJ18A has a working standoff voltage (V_WM) of 18 V, meaning it remains non-conductive below this DC or RMS voltage. This parameter is critical because it must exceed the maximum normal operating voltage of the protected line - for example, a 15V nominal supply requires ≥18V V_WM to avoid leakage-related power loss or false triggering. Exceeding V_WM initiates avalanche conduction, so margin between V_WM and system voltage ensures reliable standby behavior.

Does the 5.0SMDJ18A meet RoHS and halogen-free requirements?

Yes, the 5.0SMDJ18A is RoHS compliant and halogen-free per IEC 61249-2-21. Its molding compound contains no brominated flame retardants or chlorine-based additives, and all plating materials (matte tin leads) conform to EU Directive 2011/65/EU. These attributes support environmentally regulated industrial and consumer product certifications without requiring material declaration waivers.

What is the thermal resistance from junction to lead (R_θJL) for the 5.0SMDJ18A, and how does it impact PCB layout?

The 5.0SMDJ18A has a junction-to-lead thermal resistance (R_θJL) of 16°C/W when mounted on a standard 16mm × 16mm copper pad. This low value indicates efficient heat transfer from the silicon die to the PCB copper, enabling repeated surge events without thermal runaway. To maintain this performance, designers must implement minimum 16mm² copper pour area per lead and avoid narrow traces or thermal reliefs that increase effective R_θJA.