STMicroelectronics SMA6F18A

Overview

SMA6F18A from STMicroelectronics is a unidirectional 600 W transient voltage suppression (TVS) diode designed for primary-level surge protection in DC power rails and signal lines. It features a 18 V stand-off voltage (VRM), 29.2 V clamping voltage at 1 A (10/1000 µs), 0.2 µA leakage at 25 °C, and operates up to 175 °C junction temperature-enabling robust protection in automotive body electronics and industrial power supplies.

For engineers reviewing the SMA6F18A datasheet, SMA6F18A pinout, SMA6F18A application, or SMA6F18A equivalent, key selection criteria include clamping performance under IEC 61000-4-2 Level 4 (±25 kV contact / ±30 kV air), thermal stability at Tj = 175 °C, low dynamic resistance (0.326 Ω), and compatibility with standard SMA footprint per IPC7531.

Technical Context

The SMA6F18A employs planar silicon avalanche technology to deliver precise breakdown at 20–22.2 V (VBR min–max @ 1 mA), with clamping tightly governed by dynamic resistance (RD = 0.326 Ω) and voltage temperature coefficient (αT = 9.2 × 10⁻⁴ /°C). Its unidirectional architecture supports DC-biased protection without reverse conduction path concerns.

Designed for high-reliability environments, it sustains 400 W peak pulse power at Tj = 175 °C (10/1000 µs), exceeds IEC 61000-4-2 Level 4 ESD immunity, and maintains sub-1 µA leakage up to 85 °C-critical for low-power sensor interfaces and always-on automotive modules.

Key Specifications

Pinout & Package

The SMA6F18A is housed in an industry-standard SMA (DO-214AC) surface-mount package with matte tin-plated leads, compliant with IPC7531 footprint and JEDEC MO-136AA outline. Dimensions: 4.5 mm × 2.7 mm × 2.2 mm (L × W × H), weight 39 mg.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ18A and SMCJ18A, the SMA6F18A uniquely balances 600 W surge handling, ultra-low RD (0.326 Ω), and SMA footprint-making it optimal for space-constrained automotive and industrial modules requiring both high power density and precision clamping.

Availability

SMA6F18A is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC inputs, smart meter power supplies, and telecom remote terminal units requiring stable component supply across extended temperature and surge stress conditions.

Supply support for SMA6F18A 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, delivering innovative solutions across automotive, industrial, power, and sensing domains with strong manufacturing and R&D infrastructure.

The SMA6F series belongs to ST's Transil™ TVS portfolio, engineered specifically for high-reliability transient suppression in harsh environments where low leakage, high Tj capability, and repeatable clamping performance are mandatory.

FAQ

What is the maximum clamping voltage of SMA6F18A under a 100 A surge (8/20 µs)?

Per datasheet Figure 5 and Table 2, the clamping voltage at 100 A (8/20 µs) is approximately 39.3 V. This value is derived from the specified VCL = 39.3 V at IPP = 100 A, confirming its ability to limit voltage stress on downstream 36 V-rated components during high-current transients.

Can SMA6F18A be used in bidirectional protection circuits?

No-SMA6F18A is strictly unidirectional. For bidirectional protection, two devices must be connected anode-to-anode or a dedicated bidirectional TVS (e.g., SMA6F18CA) must be selected. Using a single unidirectional device in reverse-biased AC signal paths risks permanent breakdown.

Does SMA6F18A meet automotive qualification standards such as AEC-Q200?

While not explicitly AEC-Q200 qualified, SMA6F18A meets critical automotive stress requirements: it complies with IEC 61000-4-2 Level 4 ESD, operates up to 175 °C junction temperature, and passes JESD22-A108 temperature cycling-making it widely deployed in non-safety-critical automotive modules with additional system-level validation.

What is the recommended PCB footprint and thermal relief for SMA6F18A?

The recommended footprint follows IPC7531 and ST's Figure 13: pad length ≥3.9 mm, width ≥1.2 mm, copper area ≥2 cm² per lead. Thermal relief via ≥2 thermal spokes per pad improves solder joint reliability during reflow, especially given its 260 °C max lead temperature rating and high-power dissipation capability.