STMicroelectronics SMA4F11A

Overview

SMA4F11A from STMicroelectronics is a unidirectional 400 W transient voltage suppression (TVS) diode designed for robust ESD and surge protection in power rails and signal lines. It features a 11 V stand-off voltage (VRM), 13.7 V maximum clamping voltage at 21.8 A (10/1000 µs), 0.2 µA leakage at 25 °C, and operates up to 175 °C junction temperature-ideal for automotive body control modules and industrial I/O interfaces.

For engineers reviewing the SMA4F11A datasheet, SMA4F11A pinout, SMA4F11A application, or SMA4F11A equivalent, key selection criteria include clamping performance under 10/1000 µs surges, low-leakage behavior at elevated temperatures, unidirectional polarity compatibility with DC-biased lines, and SMA package thermal reliability per J-STD-020 MSL level 1.

Technical Context

The SMA4F11A employs planar silicon avalanche technology to deliver precise breakdown at 12.3–13.7 V (VBR min/max @ 1 mA) and tightly controlled dynamic resistance (RD = 0.216 Ω). Its clamping response is characterized for both 10/1000 µs (400 W) and 8/20 µs (2.5 kW) transients, with voltage temperature coefficient αT = 8.1 × 10⁻⁴ /°C enabling predictable VBR/VCL drift across –55 °C to +175 °C.

Designed for high-reliability DC line protection, it sustains 200 W peak pulse power at Tj = 175 °C (per Figure 3), complies with IEC 61000-4-2 Level 4 (±25 kV contact / ±30 kV air discharge), and meets UL94 V0 flammability and JEDEC-standard footprint requirements.

Key Specifications

Pinout & Package

The SMA4F11A uses the standard SMA (DO-214AC) flat package: 2.90 mm × 5.35 mm × 1.10 mm body, matte tin-plated leads, IPC7531-compliant footprint, and JEDEC registered outline. Thermal resistance R_th(j-a) is 110 °C/W on FR4 with recommended copper area (Figure 11).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ11A and 1.5SMC11A, the SMA4F11A uniquely balances compact SMA footprint, 175 °C operation, and sub-microamp leakage-making it optimal for space- and thermal-critical DC rail protection where long-term reliability under thermal stress is non-negotiable.

Availability

SMA4F11A is available at Aetrix Electronics and suitable for automotive body electronics, industrial programmable logic controller (PLC) inputs, telecom power interface protection, and medical sensor signal conditioning requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for SMA4F11A 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 intelligent power, sensing, and control solutions for automotive, industrial, and consumer markets.

The SMA4F series belongs to ST's Transil™ TVS portfolio, engineered specifically for high-reliability transient suppression in harsh thermal environments-emphasizing low leakage, stable clamping, and extended junction temperature capability.

FAQ

What is the maximum clamping voltage of SMA4F11A under a 10/1000 µs surge?

The maximum clamping voltage (V_CL) is 18 V at 21.8 A for a 10/1000 µs waveform, measured at T_amb = 25 °C. This value increases predictably with junction temperature using α_T = 8.1 × 10⁻⁴ /°C, reaching ~19.5 V at T_j = 125 °C per the datasheet's V_CL vs. T_j calculation method.

Can SMA4F11A be used in bidirectional signal line protection?

No-SMA4F11A is strictly unidirectional (anode-to-cathode conduction only). For bidirectional protection (e.g., USB, RS-485), ST offers the SMA4F11CA variant. Using SMA4F11A on AC-coupled or floating lines risks forward conduction during negative excursions, potentially damaging downstream circuitry.

Does SMA4F11A require special PCB layout considerations for thermal performance?

Yes-thermal resistance drops significantly with increased copper area under each lead. Per Figure 11, R_th(j-a) improves from ~110 °C/W (no extra copper) to ~40 °C/W with 4 cm² total copper (2 cm² per pad). Use minimum 1.5 mm wide traces and thermal vias to inner ground planes to sustain repeated 400 W pulses without exceeding 175 °C T_j.

Is SMA4F11A compliant with RoHS and REACH regulations?

Yes-SMA4F11A is manufactured in ST's ECOPACK®-compliant facilities and meets RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. The matte tin lead finish contains no lead, cadmium, mercury, hexavalent chromium, PBB, or PBDE, and conforms to J-STD-002 and JESD22-B102 E3 solderability standards.