Taiwan Semiconductor Corporation SMCJ28CAH

Overview

SMCJ28CAH from Taiwan Semiconductor is a bidirectional 28 V standoff, 1500 W surface-mount transient voltage suppressor (TVS) in DO-214AB (SMC) package, featuring 31.1–34.4 V breakdown voltage, ≤1 µA reverse leakage at 28 V, and 45.4 V clamping voltage at 34 A peak pulse current. It protects automotive and industrial power rails against ISO 7637-2 Pulse 1/2a/2b/3a/3b transients and ESD.

For engineers reviewing the SMCJ28CAH datasheet, SMCJ28CAH pinout, SMCJ28CAH application, or SMCJ28CAH equivalent, this device is selected for high-energy surge immunity in 24 V DC systems where AEC-Q101 qualification, fast <1.0 ps response, and bidirectional clamping are required.

Technical Context

The SMCJ28CAH uses a glass-passivated silicon junction optimized for low dynamic impedance and stable clamping under repetitive 10/1000 µs surge waveforms. Its bidirectional configuration enables symmetrical protection without polarity sensitivity, supporting both positive and negative transients across the same terminals.

Designed to meet ISO 7637-2 compliance, it sustains 1500 W peak pulse power at 25 °C with thermal derating above ambient, and operates over –55 °C to +150 °C junction temperature range. Junction-to-case thermal resistance is 10 °C/W, enabling effective heat dissipation in compact PCB layouts.

Key Specifications

Pinout & Package

Package: DO-214AB (SMC), surface-mount, matte tin-plated leads, polarity marked by cathode band (not functional in bidirectional configuration).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ28CA and 1.5KE28CA, the SMCJ28CAH delivers triple the peak power handling in an SMT-optimized package with automotive-grade qualification-making it the preferred choice for production 24 V systems requiring validated surge resilience.

Availability

SMCJ28CAH is available at Aetrix Electronics and suitable for automotive electronics, industrial PLCs, and telecom power feeds requiring stable component supply, AEC-Q101 compliance, and high-energy transient immunity.

Supply support for SMCJ28CAH 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, MOSFETs, and power management devices.

The SMCJ series was developed specifically for high-power, surface-mount transient suppression in automotive and industrial environments-emphasizing AEC-Q101 reliability, ISO 7637-2 compliance, and robust thermal performance in DO-214AB packaging.

FAQ

What does the 'CAH' suffix indicate in SMCJ28CAH?

The 'CAH' suffix in SMCJ28CAH denotes a bidirectional configuration ('C') with AEC-Q101 qualification ('A') and halogen-free construction ('H'). Unlike unidirectional variants (e.g., SMCJ28H), the SMCJ28CAH provides symmetrical clamping for both polarities without requiring orientation during placement. This makes it ideal for protecting AC-coupled signals or DC rails where reverse voltage transients are possible. The AEC-Q101 qualification confirms its suitability for automotive applications.

How does SMCJ28CAH differ from SMCJ28AH?

The SMCJ28CAH is bidirectional, whereas SMCJ28AH is unidirectional. Both share identical V_WM (28 V), V_BR (31.1–34.4 V), and V_C (45.4 V) specifications, but SMCJ28AH requires correct polarity alignment during PCB layout due to its cathode band marking. SMCJ28CAH eliminates polarity concerns and supports symmetric protection in differential or floating systems. Its marking code is GFG, and it complies with the same AEC-Q101 and ISO 7637-2 standards as SMCJ28AH.

Is SMCJ28CAH suitable for protecting a 24 V CAN bus interface?

Yes, SMCJ28CAH is appropriate for 24 V CAN bus protection when used across CAN_H and CAN_L or between either line and chassis ground. Its 28 V V_WM provides adequate margin above the 24 V nominal supply while allowing full CAN signal swing (±2 V differential). With 45.4 V clamping and 1500 W capability, it suppresses ESD and fast transients without disrupting bus timing. However, ensure external series resistors and common-mode chokes remain in place to preserve signal integrity-SMCJ28CAH handles energy absorption, not signal conditioning.

What is the maximum peak pulse current (I_PPM) for SMCJ28CAH, and how is it measured?

The maximum peak pulse current for SMCJ28CAH is 34 A, measured using the standardized 10/1000 µs double-exponential waveform defined in IEC 61000-4-5 and ANSI/IEEE C62.35. This current corresponds to the 1500 W peak power rating at 25 °C ambient, calculated as P_PK = V_C × I_PPM = 45.4 V × 34 A. Derating applies above 25 °C per the pulse derating curve (Fig.2), and actual I_PPM decreases linearly with rising junction temperature to maintain safe thermal limits.

Does SMCJ28CAH require a heatsink in typical PCB applications?

No, SMCJ28CAH does not require an external heatsink in standard PCB applications. Its DO-214AB (SMC) package has a junction-to-ambient thermal resistance (R_θJA) of 55 °C/W and junction-to-case (R_θJC) of 10 °C/W. When mounted on a 1-inch² 1-oz copper pad with two thermal vias, it safely dissipates repeated 1500 W pulses without exceeding +150 °C junction temperature. Thermal performance is further enhanced by its moisture sensitivity level 1 rating, which permits standard reflow profiles without pre-baking.