Taiwan Semiconductor Corporation SMDJ45CA

Overview

SMDJ45CA from Taiwan Semiconductor is a bidirectional 45 V standoff, 50.0–55.3 V breakdown, 3000 W peak pulse power Transient Voltage Suppressor in DO-214AB (SMC) package, designed for clamping ESD and lightning-induced transients in telecom power rails and industrial I/O interfaces.

For engineers reviewing the SMDJ45CA datasheet, SMDJ45CA pinout, SMDJ45CA application, or SMDJ45CA equivalent, key selection criteria include clamping voltage (72.7 V @ 41.3 A), unidirectional/bidirectional configuration, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, and thermal resistance (R_θJA = 75 °C/W).

Technical Context

SMDJ45CA is a glass-passivated, bipolar TVS diode optimized for fast transient suppression with sub-1 ps response time and bidirectional conduction symmetry. It operates across -55 °C to +175 °C junction temperature and delivers 3000 W peak pulse power under 10/1000 µs waveform per Fig.5.

The device features a single-die DO-214AB (SMC) construction with matte tin-plated leads, JESD201 Class 2 whisker resistance, and UL 94V-0 molding compound. Its 72.7 V clamping voltage at 41.3 A IPPM ensures robust protection of 48 V systems against load dump and EFT events.

Key Specifications

Pinout & Package

DO-214AB (SMC) surface-mount package with cathode band marking for polarity identification; body dimensions: 7.11 mm × 6.22 mm × 2.34 mm (L × W × H); matte tin-plated leads compliant with J-STD-002 solderability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SAC45CA and SMCJ45CA, the SMDJ45CA offers identical clamping performance and ISO 7637-2 compliance but distinguishes itself via Taiwan Semiconductor's moisture sensitivity level 1 rating and halogen-free certification per IEC 61249-2-21-critical for high-volume consumer electronics assembly.

Availability

SMDJ45CA is available at Aetrix Electronics and suitable for industrial PLC I/O protection, telecom DC power input, and automotive body control module designs requiring stable component supply and long-term lifecycle assurance.

Supply support for SMDJ45CA 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, serving global industrial, automotive, and communications markets since 1979.

The SMDJ series was developed specifically for high-reliability surface-mount surge protection in harsh environments, emphasizing low clamping ratio, fast response, and robust thermal performance in compact DO-214AB packaging.

FAQ

What is the clamping voltage of SMDJ45CA and how is it measured?

The SMDJ45CA has a maximum clamping voltage (V_C) of 72.7 V, measured at a peak pulse current (I_PPM) of 41.3 A under the standardized 10/1000 µs double-exponential waveform defined in IEC 61000-4-5. This value is guaranteed across the full operating temperature range (-55 °C to +175 °C) and reflects worst-case device behavior during surge events. The SMDJ45CA achieves this clamping performance while maintaining tight V_BR tolerance (50.0–55.3 V) and low leakage (<1 µA at 45 V).

Is SMDJ45CA unidirectional or bidirectional, and how does that affect circuit placement?

SMDJ45CA is a bidirectional TVS diode, indicated by the "CA" suffix, meaning it provides symmetrical clamping for both positive and negative transients without polarity sensitivity. This allows placement across any two nodes requiring transient suppression-such as AC-coupled signal lines, floating power domains, or differential buses-without concern for orientation. Unlike unidirectional variants (e.g., SMDJ45A), the SMDJ45CA eliminates the need for cathode alignment during automated placement, simplifying PCB layout and reducing assembly errors.

Does SMDJ45CA meet automotive surge immunity standards like ISO 7637-2?

Yes, the SMDJ45CA meets ISO 7637-2 requirements for Pulse 1 (inductive load dump), Pulse 2a/2b (battery disconnection), and Pulse 3a/3b (capacitive coupling and EFT). Its 3000 W peak pulse power rating, sub-1 ps response time, and 72.7 V clamping voltage ensure reliable protection of 12 V and 48 V automotive subsystems-including body control modules and infotainment power rails-against real-world vehicle electrical disturbances. The SMDJ45CA's specified R_θJA of 75 °C/W further supports sustained operation in under-hood thermal environments.

What is the thermal resistance of SMDJ45CA and why does it matter for PCB layout?

The SMDJ45CA has a junction-to-ambient thermal resistance (R_θJA) of 75 °C/W and a junction-to-lead resistance (R_θJL) of 15 °C/W. These values directly impact PCB copper area requirements: to maintain T_J ≤ 175 °C during repeated 3000 W surges, designers must allocate ≥120 mm² of 2 oz copper connected to both terminals. The low R_θJL confirms efficient heat transfer into the PCB, making thermal relief design critical-especially in enclosed industrial enclosures where ambient temperatures exceed 70 °C. The SMDJ45CA's thermal specs are validated per JEDEC JESD51-2.

Can SMDJ45CA be used in place of SMDJ43CA or SMDJ48CA without redesigning the PCB?

No-while SMDJ45CA shares the DO-214AB (SMC) package with SMDJ43CA and SMDJ48CA, its 45 V working voltage is specifically matched to 48 V nominal systems. Substituting with SMDJ43CA (43 V V_WM) risks premature clamping and increased leakage in steady-state operation; using SMDJ48CA (48 V V_WM) may allow damaging overvoltage during transients due to higher V_BR (53.3–58.9 V). The SMDJ45CA's precise 45 V V_WM and 50.0–55.3 V V_BR ensure optimal margin for 48 V telecom and industrial applications without compromising reliability or efficiency.