Taiwan Semiconductor Corporation SMBJ58A

Overview

SMBJ58A 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 58 V working stand-off voltage (VWM), 64.4–71.2 V breakdown voltage (VBR), 93.6 V maximum clamping voltage (VC) at 6.7 A peak pulse current, and 600 W peak pulse power rating with <1.0 ps response time. It is used in automotive power supply inputs and industrial I/O interfaces to protect downstream ICs from ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.

For engineers reviewing the SMBJ58A datasheet, SMBJ58A pinout, SMBJ58A application, or SMBJ58A equivalent, key selection criteria include clamping voltage margin relative to protected IC's absolute maximum rating, leakage current at operating voltage, thermal derating above 25°C ambient, and compatibility with DO-214AA (SMB) PCB footprint and reflow profiles.

Technical Context

The SMBJ58A operates as a unidirectional avalanche diode, conducting only during reverse overvoltage events while presenting high impedance under normal bias. Its glass-passivated junction ensures stable VBR and low leakage (<1 µA at 58 V), and its 10 °C/W junction-to-case thermal resistance supports sustained surge handling when mounted on thermally adequate copper.

It meets ISO 7637-2 test pulses 1 (inductive load dump), 2a/2b (battery disconnect/relay bounce), and 3a/3b (capacitive coupling), with clamping performance validated using 10/1000 µs waveform per ANSI/IEEE C62.35. The device is rated for -55°C to +150°C junction temperature and complies with J-STD-020 moisture sensitivity level 1.

Key Specifications

Pinout & Package

Package: DO-214AA (SMB), surface-mount, single-die unidirectional configuration. Cathode indicated by molded band on case. Matte tin-plated leads, RoHS and halogen-free compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ58A, SMAJ58A trades thermal performance for smaller footprint, while SMCJ58A delivers higher surge capacity in a larger package-enabling trade-offs between PCB area, thermal management, and design margin without changing circuit function.

Availability

SMBJ58A is available at Aetrix Electronics and suitable for automotive electronics, industrial PLCs, LED lighting systems, and telecom infrastructure requiring stable component supply and full traceability.

Supply support for SMBJ58A 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 semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs for industrial and automotive markets.

The SMBJ series was developed specifically for high-reliability, surface-mount surge protection in harsh environments-emphasizing low clamping voltage, fast response, and robust thermal performance in compact DO-214AA packages.

FAQ

What is the clamping voltage of SMBJ58A and why does it matter?

The SMBJ58A has a maximum clamping voltage (VC) of 93.6 V at 6.7 A peak pulse current (10/1000 µs waveform). This value defines the highest voltage that will appear across the protected circuit during a surge event. It matters because it must remain below the absolute maximum voltage rating of downstream components-such as DC-DC controllers or microcontrollers-to prevent damage or malfunction. For example, pairing SMBJ58A with a 100 V-rated IC provides 6.4 V design margin.

Is SMBJ58A unidirectional or bidirectional, and how can I tell?

SMBJ58A is a unidirectional TVS diode, confirmed by its part number suffix "A" (per Taiwan Semiconductor's naming convention) and electrical specifications listing only one VBR range (64.4–71.2 V) without dual-direction symmetry. It features a cathode band marking and conducts only when the cathode is positive relative to the anode-making it suitable for DC rail protection where polarity is fixed. Bidirectional variants use "C" or "CA" suffixes.

What is the leakage current of SMBJ58A at its working voltage?

The SMBJ58A exhibits a maximum blocking leakage current (ID) of less than 1 µA at its 58 V working stand-off voltage (VWM), measured at 25°C. This ultra-low leakage ensures minimal power loss and no measurable loading on the protected 58 V rail, making SMBJ58A appropriate for always-on systems such as automotive body modules or remote sensors where standby current budget is critical.

Does SMBJ58A meet automotive surge immunity standards?

Yes, SMBJ58A meets ISO 7637-2 for automotive transient immunity, covering Pulse 1 (inductive load dump), Pulse 2a (battery disconnect), Pulse 2b (relay bounce), and Pulses 3a/3b (capacitive coupling). Its 600 W peak pulse power rating and verified clamping behavior under 10/1000 µs waveforms make it suitable for front-end protection in ECUs, infotainment systems, and ADAS power supplies.

What is the thermal resistance of SMBJ58A and how does it affect layout?

SMBJ58A has a junction-to-ambient thermal resistance (RθJA) of 55 °C/W and junction-to-case (RθJC) of 10 °C/W. These values mean that under sustained surge conditions, PCB copper area and thermal vias directly beneath the DO-214AA (SMB) package significantly impact temperature rise. To maintain TJ ≤150°C during repeated events, designers should allocate ≥40 mm² of 2 oz copper connected to both terminals with ≥4 thermal vias (0.3 mm diameter) per pad.