STMicroelectronics SMB6F28A

Overview

SMB6F28A 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 standoff voltage (VRM) of 28 V, clamping voltage (VCL) of 45.4 V at 13.8 A (10/1000 µs), and operates up to 175 °C junction temperature - enabling robust protection in automotive body electronics and industrial power supplies.

For engineers reviewing the SMB6F28A datasheet, SMB6F28A pinout, SMB6F28A application, or SMB6F28A equivalent, key selection criteria include its low leakage current (0.2 µA @ 25 °C), flat SMB package with 1 mm profile, IEC 61000-4-2 ±30 kV ESD immunity, and dynamic resistance of 0.804 Ω - critical for low-voltage rail clamping integrity under fast transients.

Technical Context

The SMB6F28A employs planar silicon avalanche technology to deliver precise breakdown behavior and stable clamping across temperature. Its unidirectional configuration supports DC-biased protection paths, with VBR specified at 31.1–34.3 V (min–max @ 25 °C) and temperature coefficient αT = 9.8 × 10⁻⁴ /°C.

It meets IEC 61000-4-4 Level 4 (±4 kV) and exceeds IEC 61000-4-2 Level 4 for both contact and air discharge (±30 kV). The device sustains 470 W peak pulse power at Tj = 175 °C (10/1000 µs), leveraging low thermal resistance (Rth(j-a) ≈ 120 °C/W on standard FR4 footprint) for sustained surge handling.

Key Specifications

Pinout & Package

The SMB6F28A is housed in an SMB Flat package (JEDEC MO-136AC), measuring 3.95 × 5.60 × 1.10 mm with a 1 mm profile optimized for space-constrained PCB layouts. The package features matte tin-plated leads compliant with J-STD-002 and IPC7531 footprints.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ28A, SMB6F28A offers identical protection performance with enhanced manufacturability and RoHS compliance; versus SMA6F28A, it delivers 50% higher surge power handling and 6% lower clamping voltage - directly improving safety margin for 24 V systems.

Availability

SMB6F28A is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC inputs, telecom PoE equipment, and medical auxiliary power supplies requiring stable component supply across multi-year production cycles.

Supply support for SMB6F28A 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 automotive, industrial, and power discrete technologies with over 40 years of TVS innovation.

The SMB6FxxA series belongs to ST's high-reliability transient protection portfolio, engineered specifically for demanding DC rail protection where low leakage, high-temperature stability, and repeatable clamping are mandatory - not general-purpose surge suppression.

FAQ

What is the maximum surge current the SMB6F28A can handle?

The SMB6F28A sustains 13.8 A peak pulse current (IPP) under 10/1000 µs waveform at 25 °C, and up to 68 A under 8/20 µs waveform. At elevated junction temperatures (175 °C), its derated IPP remains 59 A (8/20 µs), verified per Figure 5 in DS12898 Rev 2.

Does SMB6F28A require a heatsink for standard PCB mounting?

No heatsink is required. On a standard FR4 PCB with 1 cm² copper area per lead, its thermal resistance is ~120 °C/W. With 600 W surge energy applied for <1 ms, junction temperature rise stays below 100 °C - well within the 175 °C limit, per Figure 10 and 11 in the datasheet.

How does SMB6F28A compare to bidirectional TVS diodes in 24 V systems?

SMB6F28A is unidirectional and intended for DC-biased lines (e.g., +24 V to GND). Bidirectional variants like SMB6F28CA have symmetric clamping but higher capacitance and leakage - making SMB6F28A preferable for low-noise, low-leakage 24 V power rails where polarity is fixed and ESD directionality is known.

Is SMB6F28A compatible with lead-free reflow soldering?

Yes. It is qualified for lead-free reflow per J-STD-020 MSL Level 1, with peak temperature tolerance up to 245 °C for 20–40 seconds. The recommended profile (Figure 20) specifies ramp rates ≤3 °C/s and dwell time at peak ≤60 s - fully aligned with standard Pb-free assembly processes.