Taiwan Semiconductor Corporation SMCJ170A

Overview

SMCJ170A from Taiwan Semiconductor is a unidirectional 1500W surface-mount transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, with 170V working stand-off voltage (VWM), 189–209V breakdown voltage (VBR), and 275V maximum clamping voltage (VC) at 5.7A peak impulse current. It protects automotive power rails and industrial I/O interfaces against ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.

For engineers reviewing the SMCJ170A datasheet, SMCJ170A pinout, SMCJ170A application, or SMCJ170A equivalent, key selection criteria include clamping performance under 10/1000μs surge, thermal resistance (R_θJC = 10°C/W), unidirectional polarity marking, and compliance with JESD201 Class 2 whisker resistance and UL 94V-0 molding compound.

Technical Context

The SMCJ170A uses a glass-passivated silicon junction optimized for fast response (<1.0ps rise time from 0V to V_BR(min)) and low leakage (<1μA @ 170V). Its unidirectional configuration enables asymmetric protection of DC power lines without reverse conduction during normal operation.

Designed for 8.3ms half-sine surge immunity per IEC 61000-4-5 and ISO 7637-2, it delivers 1500W peak pulse power at T_A = 25°C with derating above ambient-supported by R_θJA = 55°C/W and R_θJC = 10°C/W thermal metrics.

Key Specifications

Pinout & Package

DO-214AB (SMC) package: molded plastic case with matte tin-plated leads, cathode band marking polarity, 0.210g weight, and UL 94V-0 flammability rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ170A and 1.5KE170A, the SMCJ170A provides superior surge handling (1500W vs. 600W/1500W), SMT compatibility, and certified whisker resistance-making it the preferred choice for new automotive and industrial PCB designs requiring ISO 7637-2 compliance and automated manufacturing.

Availability

SMCJ170A is available at Aetrix Electronics and suitable for automotive electronics, industrial control systems, and LED lighting applications requiring stable component supply and full ISO 7637-2 transient immunity certification.

Supply support for SMCJ170A 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 analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, and protection devices since 1979.

The SMCJ series was developed specifically for high-energy transient suppression in automotive and industrial environments, emphasizing rugged packaging, tight VBR tolerances, and standardized SMT compatibility across 5V–170V ratings.

FAQ

What is the clamping voltage of the SMCJ170A at its rated peak pulse current?

The SMCJ170A has a maximum clamping voltage (V_C) of 275 V at 5.7 A peak impulse current (I_PPM), measured under the 10/1000μs standard surge waveform. This value defines the upper voltage limit imposed on protected circuitry during transient events and is critical for ensuring downstream components remain within their absolute maximum ratings. The SMCJ170A achieves this clamping performance while maintaining low leakage (<1 μA at 170 V) and fast response (<1.0 ps).

Is the SMCJ170A unidirectional or bidirectional, and how is polarity identified?

The SMCJ170A is a unidirectional TVS diode, designed for DC line protection where reverse conduction is not required. Polarity is marked by a cathode band on the DO-214AB (SMC) package body-this band identifies the cathode terminal, which must be connected to the line being protected (e.g., +24V rail), while the anode connects to ground. Bidirectional variants use the "CA" suffix (e.g., SMCJ170CA), which is not applicable to the SMCJ170A.

Does the SMCJ170A meet automotive transient immunity standards such as ISO 7637-2?

Yes, the SMCJ170A is explicitly rated to meet ISO 7637-2 Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) requirements. Its 1500W peak pulse power rating, fast response time (<1.0 ps), and specified clamping behavior under standardized surge waveforms make it suitable for protecting ECUs, body control modules, and other automotive electronics subjected to real-world vehicle electrical disturbances.

What is the thermal resistance profile of the SMCJ170A, and how does it affect PCB layout?

The SMCJ170A has a junction-to-case thermal resistance (R_θJC) of 10°C/W and junction-to-ambient resistance (R_θJA) of 55°C/W at standard SMT mounting conditions. To maintain safe operation near its 150°C maximum junction temperature, PCB layout must provide adequate copper pour area under the cathode/anode pads and minimize trace length to ground planes. Thermal vias beneath the pads are recommended for high-duty-cycle surge environments to enhance heat dissipation beyond the baseline R_θJA.

How does the SMCJ170A compare to the SMCJ170 (non-A) variant in terms of electrical performance?

The SMCJ170A offers tighter breakdown voltage tolerance versus the base SMCJ170: V_BR = 189–209 V (min/max) at 1 mA for the "A" version, compared to 189–231 V for the non-A part. This narrower V_BR range improves consistency in clamping onset across production lots and reduces design margin uncertainty. Both share identical V_WM (170 V), V_C (275 V / 304 V), and package (DO-214AB), but the SMCJ170A is preferred for precision-sensitive applications like automotive power rail protection where predictable turn-on voltage is critical.