STMicroelectronics SMCJ70A-TR

Overview

SMCJ70A-TR from STMicroelectronics is a unidirectional 1500 W transient voltage suppression diode in SMC package, designed for primary-level surge protection of DC power rails and signal lines against IEC 61000-4-2 ESD (±30 kV air/contact) and IEC 61000-4-4 EFT (4 kV). It features a 70 V standoff voltage (VRM), 77.8 V minimum breakdown voltage (VBR), and clamps to 113 V at 13.9 A (10/1000 µs), with leakage current ≤0.2 µA at 25 °C and junction temperature rating up to +150 °C.

For engineers reviewing the SMCJ70A-TR datasheet, SMCJ70A-TR pinout, SMCJ70A-TR application, or SMCJ70A-TR equivalent, this device is selected for high-reliability industrial power supply input stages, telecom line interface protection, and automotive body control modules where low-leakage, high-temperature operation, and repeatable clamping performance under repetitive surges are critical.

Technical Context

This unidirectional TVS diode operates as a voltage-clamped shunt protector: it remains high-impedance below VRM = 70 V, then avalanches sharply at VBR ≥77.8 V to divert surge current away from downstream circuitry. Its planar junction construction enables stable leakage (<0.2 µA) and predictable thermal derating-power capability drops from 1500 W at 25 °C to 1250 W at Tj = 150 °C (10/1000 µs).

The device complies with IEC 61000-4-2 Level 4 (±30 kV), IEC 61000-4-4 Level 4 (4 kV), and UL94 V0 flammability standards. Its SMC package supports JEDEC-standard reflow (peak 240–245 °C), IPC7531 footprint, and MSL level 1 handling-enabling robust automated assembly without moisture sensitivity concerns.

Key Specifications

Pinout & Package

The SMCJ70A-TR is housed in an SMC (DO-214AB) surface-mount package with two terminals: Cathode (marked band) and Anode. The package measures 5.55–6.25 mm × 7.75–8.15 mm × 2.45 mm max height, with gull-wing leads optimized for FR4 PCBs using 70 µm copper and IPC7531-compliant footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TVS diode applications.

Compared with SMBJ70A-TR and 1.5KE70A, the SMCJ70A-TR delivers optimal balance of high surge capacity (1500 W), ultra-low leakage (0.2 µA), and SMT manufacturability-making it preferred for new industrial and automotive designs requiring both reliability and assembly scalability.

Availability

SMCJ70A-TR is available at Aetrix Electronics and suitable for industrial power supply inputs, telecom line interfaces, and automotive body control modules requiring stable component supply, long-term lifecycle support, and compliance with IEC 61000-4-2/4-4 immunity standards.

Supply support for SMCJ70A-TR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, MEMS, and microcontrollers for industrial, automotive, and consumer markets.

The SMCJ series belongs to ST's high-power TVS diode portfolio, engineered specifically for robust front-end surge protection in harsh-environment applications where thermal stability, low leakage, and repeatable clamping performance are non-negotiable.

FAQ

What is the maximum clamping voltage of SMCJ70A-TR under a 10/1000 µs surge?

The maximum clamping voltage (V_CL) is 113 V at 13.9 A for a 10/1000 µs waveform, measured at T_j = 25 °C. This value increases with junction temperature due to the α_T coefficient (10.5 × 10⁻⁴/°C), reaching ~122 V at 150 °C-critical for margining downstream component voltage ratings.

Can SMCJ70A-TR be used in bidirectional signal protection?

No-SMCJ70A-TR is unidirectional and must be connected with cathode toward the protected line and anode to ground. For bidirectional protection (e.g., RS-485), the SMCJ70CA-TR variant is required, which provides symmetrical clamping for both polarities.

What is the recommended PCB footprint for SMCJ70A-TR?

The official footprint follows IPC7531 and JEDEC DO-214AB standards: pad length 5.11 mm, pad width 1.54 mm, center-to-center spacing 8.19 mm, with 3.14 mm overall width. Thermal relief vias under pads are recommended to enhance heat dissipation during repetitive surges.

Does SMCJ70A-TR require special handling during reflow soldering?

No-it is rated MSL Level 1 and compatible with standard lead-free reflow profiles peaking at 240–245 °C (per J-STD-020). The recommended profile includes ramp-up ≤3 °C/s, soak at 150–200 °C for 60–90 s, and peak dwell ≤60 s-no pre-baking or dry-pack is needed.