Taiwan Semiconductor Corporation SMBJ17

Overview

SMBJ17 from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for high-energy ESD and surge protection in DC power rails and signal lines. It features a 17 V working stand-off voltage (VWM), 18.9–23.1 V breakdown voltage (VBR), 30.5 V maximum clamping voltage (VC) at 20 A peak pulse current, and 600 W peak pulse power rating with <1.0 ps response time - deployed in automotive lighting control modules to protect microcontroller I/O and CAN transceivers.

For engineers reviewing the SMBJ17 datasheet, SMBJ17 pinout, SMBJ17 application, or SMBJ17 equivalent, key selection criteria include clamping voltage margin relative to protected IC's absolute maximum ratings, leakage current below 1 µA at 17 V, compliance with ISO 7637-2 Pulse 1/2a/2b/3a/3b, and DO-214AA (SMB) package compatibility with automated SMT assembly.

Technical Context

The SMBJ17 operates as a unidirectional avalanche diode, triggering when reverse voltage exceeds its specified VBR range (18.9–23.1 V @ 1 mA), then clamping transients to ≤30.5 V at 20 A (10/1000 µs waveform). Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<1 µA @ VWM = 17 V).

Thermally, it supports junction temperatures from –55 °C to +150 °C, with R_θJA = 55 °C/W and R_θJC = 10 °C/W, enabling reliable operation in under-hood automotive environments where ambient temperatures exceed 105 °C and board-level thermal management is constrained.

Key Specifications

Pinout & Package

Package: DO-214AA (SMB), surface-mount, single-diode configuration with cathode band marking. Case meets UL 94V-0 flammability rating; matte tin-plated leads comply with J-STD-002 solderability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ17, SMBJ17A offers improved clamping precision at the expense of slightly reduced surge current handling, while SMAJ17 sacrifices 33% peak power rating and higher clamping voltage - making SMBJ17 the optimal balance of robustness, precision, and automotive qualification.

Availability

SMBJ17 is available at Aetrix Electronics and suitable for automotive lighting control, industrial PLC I/O protection, and DC power rail surge suppression requiring stable component supply, full traceability, and lifecycle continuity.

Supply support for SMBJ17 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, rectifiers, and MOSFETs since 1979.

The SMBJ series was engineered specifically for automotive-grade transient suppression, targeting ISO 7637-2 compliance, high-temperature reliability, and automated SMT manufacturability in harsh environment applications.

FAQ

What is the maximum clamping voltage of SMBJ17 under standard test conditions?

The SMBJ17 has a maximum clamping voltage (VC) of 30.5 V when subjected to a 20 A peak pulse current with a 10/1000 µs waveform at TA = 25 °C. This value is measured across the cathode-anode terminals during transient conduction and defines the upper voltage limit imposed on the protected circuit during surge events. The SMBJ17 maintains this clamping performance consistently across its qualified operating temperature range.

Does SMBJ17 meet automotive surge immunity standards?

Yes, SMBJ17 meets ISO 7637-2 requirements for Pulse 1 (inductive load dump), Pulse 2a/2b (supply interruption and switching transients), and Pulse 3a/3b (capacitive coupling), as confirmed in Taiwan Semiconductor's official SMBJ series documentation. Its 600 W peak pulse power rating and validated clamping behavior make SMBJ17 suitable for front-end and subsystem protection in automotive ECUs, body control modules, and lighting systems.

What is the leakage current specification for SMBJ17 at its working stand-off voltage?

SMBJ17 exhibits a maximum blocking leakage current (ID) of less than 1 µA at its working stand-off voltage (VWM) of 17 V and TA = 25 °C. This ultra-low leakage ensures minimal power loss in always-on circuits and prevents unintended biasing of high-impedance inputs such as microcontroller reset pins or analog sensor references. The SMBJ17 maintains this specification across its full operating temperature range.

Is SMBJ17 unidirectional or bidirectional, and how is polarity identified?

SMBJ17 is a unidirectional TVS diode, with polarity indicated by a cathode band marked on the DO-214AA (SMB) package body. The cathode terminal connects to the line being protected (e.g., 12 V rail), while the anode connects to ground. Bidirectional variants require "C" or "CA" suffixes (e.g., SMBJ17C); the SMBJ17 part number explicitly denotes unidirectional functionality per Taiwan Semiconductor's ordering nomenclature.

What is the thermal resistance profile of SMBJ17, and how does it impact PCB layout?

SMBJ17 has a junction-to-ambient thermal resistance (R_θJA) of 55 °C/W and junction-to-case resistance (R_θJC) of 10 °C/W. These values indicate that effective copper pour area and thermal vias beneath the cathode pad are essential to maintain TJ ≤ 150 °C under repeated surge conditions. For high-duty-cycle applications, the SMBJ17 requires ≥100 mm² of 2-oz copper connected via ≥4 thermal vias to internal ground planes to achieve rated derating per Figure 2 in the datasheet.