Taiwan Semiconductor Corporation SMCJ45H

Overview

SMCJ45H from Taiwan Semiconductor is a unidirectional 1500W surface-mount transient voltage suppressor (TVS) diode in DO-214AB (SMC) package, with 45V working stand-off voltage (VWM), 50–61.1V breakdown voltage (VBR), and 80.3V maximum clamping voltage (VC) at 19A peak pulse current. It delivers AEC-Q101 qualification and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive load-dump and ESD protection in power rails.

For engineers reviewing the SMCJ45H datasheet, SMCJ45H pinout, SMCJ45H application, or SMCJ45H equivalent, this page provides verified electrical parameters, thermal resistance (R_θJA = 55°C/W), clamping performance under 10/1000µs surge, polarity marking, and RoHS/halogen-free compliance - all critical for automotive front-end, industrial DC bus, and telecom port hardening designs.

Technical Context

The SMCJ45H operates as a unidirectional avalanche diode, activated only during reverse overvoltage events above its VBR threshold. Its glass-passivated junction ensures stable breakdown and low leakage (<1µA at 45V), while fast response (<1.0ps) enables effective suppression of ESD and lightning-induced transients per IEC 61000-4-2/4-5.

Thermally, it features R_θJC = 10°C/W and R_θJA = 55°C/W, supporting 5W steady-state dissipation at 25°C ambient. The device is rated for junction temperatures from –55°C to +150°C and complies with JESD201 Class 2 whisker resistance and J-STD-020 Level 1 moisture sensitivity.

Key Specifications

Pinout & Package

DO-214AB (SMC) surface-mount package with cathode band marking on one end; matte tin-plated leads compliant with J-STD-002 solderability and JESD201 Class 2 whisker resistance. Weight: 0.210 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ45A and SMF45A, the SMCJ45H uniquely combines 1500W surge capacity, AEC-Q101 qualification, and DO-214AB mechanical robustness - making it the only option among the three capable of surviving automotive load-dump without derating or parallel staging.

Availability

SMCJ45H is available at Aetrix Electronics and suitable for automotive power distribution, industrial 48V DC bus protection, and telecom Ethernet port hardening requiring stable component supply, full traceability, and long-lifecycle support.

Supply support for SMCJ45H 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 power MOSFETs for automotive and industrial markets.

The SMCJ series was designed specifically for high-energy transient suppression in harsh environments - emphasizing AEC-Q101 reliability, ISO 7637-2 compliance, and robust thermal performance in surface-mount packages.

FAQ

What is the clamping voltage of SMCJ45H at its rated peak pulse current?

The SMCJ45H has a maximum clamping voltage (VC) of 80.3 V at 19 A peak pulse current (IPPM), measured under the standard 10/1000 µs double-exponential waveform. This value is guaranteed across temperature and process variation, ensuring downstream components see no more than 80.3 V during surge events. The SMCJ45H maintains this clamping performance consistently due to its glass-passivated junction and optimized die geometry.

Is SMCJ45H suitable for bidirectional transient protection?

No, SMCJ45H is a unidirectional TVS diode intended for DC rail protection where polarity is fixed. For bidirectional applications - such as AC lines or data buses requiring symmetrical clamping - the bipolar variant SMCJ45AH (with CH or CAH suffix) must be used. The SMCJ45H features a cathode band marking and conducts only in forward direction; using it in reverse-biased AC configurations will result in permanent failure.

Does SMCJ45H meet automotive qualification standards?

Yes, SMCJ45H is AEC-Q101 qualified and explicitly tested to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b transient immunity requirements. Its construction - including glass-passivated junction, matte tin plating, and DO-214AB mechanical robustness - satisfies automotive environmental stress testing for temperature cycling, humidity, and mechanical shock. The SMCJ45H is approved for use in engine control units, body electronics, and ADAS power supplies.

What is the maximum steady-state power dissipation for SMCJ45H?

The SMCJ45H has a steady-state power dissipation (PD) rating of 5 W at TA = 25°C, derated linearly above that ambient temperature per the published derating curve (Fig.2). This rating applies only to continuous DC or low-frequency reverse leakage conditions - not transient events. In normal operation at 45 V stand-off, its reverse leakage remains below 1 µA, resulting in sub-50 µW static power loss. The SMCJ45H relies on its 1500 W peak pulse rating for transient energy absorption, not sustained power handling.

How does the thermal resistance of SMCJ45H affect PCB layout?

The SMCJ45H has R_θJA = 55°C/W and R_θJC = 10°C/W, meaning effective heat transfer depends heavily on copper area connected to its pads. To maintain TJ ≤ 150°C at full 5 W steady-state dissipation, ≥ 250 mm² of 1 oz. copper per pad is recommended. For transient-only use (typical), minimal copper suffices - but automotive applications demand thermal vias and internal planes per TSC's suggested pad layout. The SMCJ45H's DO-214AB footprint allows direct integration into high-reliability layouts without thermal compromise.