Taiwan Semiconductor Corporation SMBJ45C

Overview

SMBJ45C from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AA (SMB) package, rated for 600W peak pulse power, 45V working stand-off voltage (V_WM), and clamping voltage of 80.3V at 7.8A peak impulse current. It protects automotive and industrial power rails against ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.

For engineers reviewing the SMBJ45C datasheet, SMBJ45C pinout, SMBJ45C application, or SMBJ45C equivalent, key selection criteria include clamping voltage margin relative to protected IC V_CC, leakage current below 1µA at 45V, bidirectional capability confirmation (C suffix denotes bipolar configuration), and thermal derating above 25°C ambient per R_θJA = 55°C/W.

Technical Context

The SMBJ45C is a silicon avalanche diode designed for fast clamping of high-energy transients using a glass-passivated junction. Its sub-1ps response time ensures protection before downstream ICs experience overvoltage stress, while its 150°C maximum junction temperature supports operation in under-hood automotive environments.

As a bidirectional TVS (denoted by "C" suffix), SMBJ45C provides symmetrical clamping in both polarities - critical for AC-coupled signal lines or floating bus systems. Electrical characteristics apply identically in forward and reverse directions, eliminating polarity-dependent design constraints during layout.

Key Specifications

Pinout & Package

DO-214AA (SMB) surface-mount package with cathode band marking; matte tin-plated leads compliant with J-STD-002 solderability requirements and JESD201 Class 2 whisker resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ45C, SMAJ45CA offers lower clamping voltage but reduced thermal performance, while 1.5SMC47CA delivers greater surge capacity at the cost of larger size and higher V_WM; SMBJ45C balances compact SMB footprint, precise 45V standoff, and proven automotive qualification.

Availability

SMBJ45C is available at Aetrix Electronics and suitable for automotive electronics, industrial PLCs, and LED lighting systems requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for SMBJ45C 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, and rectifiers with global AEC-Q200 qualification capabilities.

The SMBJ series was developed specifically for robust transient suppression in harsh automotive and industrial environments, emphasizing low clamping ratio, high reliability under thermal cycling, and compliance with ISO 7637-2 and J-STD-020 standards.

FAQ

What does the "C" suffix in SMBJ45C indicate?

The "C" suffix in SMBJ45C denotes a bidirectional configuration - meaning the device functions identically in both polarities, with symmetrical breakdown and clamping characteristics. Unlike unidirectional SMBJ45A, SMBJ45C has no designated anode or cathode for surge protection; both terminals clamp equally above ±50.0V. This makes SMBJ45C ideal for AC signal lines or floating buses where polarity reversal may occur.

What is the maximum clamping voltage of SMBJ45C under standard test conditions?

The maximum clamping voltage of SMBJ45C is 80.3 V, measured at a peak impulse current (I_PP) of 7.8 A with a 10/1000 µs waveform. This value represents the worst-case voltage imposed on the protected circuit during a standardized surge event and must be compared against the absolute maximum ratings of downstream components to ensure safe operation.

Is SMBJ45C suitable for automotive applications requiring ISO 7637-2 compliance?

Yes, SMBJ45C is explicitly rated to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b test requirements. Its 600W peak pulse power rating, fast <1 ps response time, and 150°C junction temperature capability align with automotive ECU and body control module protection needs. Taiwan Semiconductor qualifies the SMBJ series for AEC-Q200 stress testing, confirming suitability for under-hood and chassis-mounted systems.

How does SMBJ45C differ from SMBJ45A in terms of electrical behavior?

SMBJ45C is bidirectional with identical V_BR and V_C in both directions, while SMBJ45A is unidirectional - conducting only when cathode is positive relative to anode. SMBJ45A exhibits forward voltage (~3.5 V at 50 A) in one direction but blocks in reverse until breakdown; SMBJ45C has no forward conduction path and clamps symmetrically at ±50.0 V. Layout and system grounding assumptions differ significantly between the two variants.

What is the leakage current specification for SMBJ45C at its working voltage?

The maximum blocking leakage current (I_D) for SMBJ45C is 1 µA when biased at its working stand-off voltage (V_WM) of 45 V. This ultra-low leakage ensures minimal power loss in always-on systems and avoids interference with high-impedance sensing nodes or precision reference circuits. The value is guaranteed across the full operating temperature range of −55°C to +150°C.