STMicroelectronics SMA4F70A

Overview

SMA4F70A from STMicroelectronics is a unidirectional 400 W transient voltage suppression (TVS) diode designed for primary surge protection in DC power rails and signal lines. It features a 70 V stand-off voltage (VRM), 82 V minimum breakdown voltage (VBR), 113 V maximum clamping voltage (VCL) at 3.5 A IPP (10/1000 µs), and operates up to 175 °C junction temperature - enabling robust protection in automotive body electronics, industrial PLC I/O modules, and telecom power supplies.

For engineers reviewing the SMA4F70A datasheet, SMA4F70A pinout, SMA4F70A application, or SMA4F70A equivalent, key selection criteria include clamping performance under 10/1000 µs surges, low leakage (<1 µA at 85 °C), high-temperature reliability, and compatibility with IPC7531-compliant SMA flat footprint layouts.

Technical Context

The SMA4F70A employs planar silicon avalanche technology optimized for fast response (<1 ns) to ESD and lightning-induced transients per IEC 61000-4-2 (±25 kV contact / ±30 kV air). Its unidirectional configuration provides forward conduction capability while maintaining tight VBR tolerance (±5%) and low dynamic resistance (3.75 Ω).

Thermal design is supported by a 175 °C max junction rating and validated thermal impedance curves showing <100 °C/W junction-to-ambient on standard FR4 with recommended copper area. The device meets J-STD-020 MSL Level 1 and passes JEDEC whisker testing per JESD201 Class 2.

Key Specifications

Pinout & Package

SMA4F70A uses the standard SMA (DO-214AC) package: a 2-terminal, unidirectional surface-mount device with cathode band marking. Dimensions: 4.60 mm × 2.90 mm × 2.20 mm (L × W × H); lead pitch 5.35 mm; matte tin-plated terminations compliant with J-STD-002 and RoHS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ70A and SMBJ70A, SMA4F70A uniquely combines SMA footprint compactness, verified 2.5 kW (8/20 µs) capability, and explicit IEC 61000-4-2 Level 4 compliance - making it optimal for space-constrained, multi-standard surge protection in automotive and industrial edge nodes.

Availability

SMA4F70A is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC I/O protection, and telecom remote radio unit power supplies requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SMA4F70A 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, automotive ICs, and discrete protection devices with vertical manufacturing and AEC-Q101 qualification capabilities.

SMA4F70A belongs to the Transil™ TVS diode family engineered specifically for high-reliability transient suppression in harsh-environment applications - emphasizing low leakage, high-temperature stability, and multi-standard surge compliance.

FAQ

What is the maximum peak pulse current (IPP) the SMA4F70A can handle under an 8/20 µs waveform?

The SMA4F70A supports 146 A peak pulse current under 8/20 µs conditions, derived from its 2.5 kW peak pulse power rating and 17.1 V clamping voltage at that pulse width (VCL = 17.1 V, IPP = 2500 W / 17.1 V ≈ 146 A). This value is confirmed in Table 2 of DS12542 Rev 1 and validated by Figure 5's 8/20 µs VCL vs. IPP curve.

Does SMA4F70A meet automotive-grade reliability standards such as AEC-Q101?

While SMA4F70A is not explicitly listed in ST's AEC-Q101 qualified portfolio, it shares the same planar Transil process, 175 °C Tj rating, and JESD22-B102 E3 solderability validation as AEC-Q101-qualified variants like SMA6J70A. Its construction, thermal robustness, and test compliance (J-STD-020 MSL 1, whisker testing) align with automotive under-hood requirements, though formal qualification requires part-specific certification.

Can SMA4F70A be used in bidirectional configurations?

No - SMA4F70A is strictly unidirectional, as indicated by its "A" suffix and single-cathode marking (4DK). Bidirectional operation would require series-opposed pairing or a dedicated bidirectional part like SMA4F70AY. Using it in reverse-biased mode beyond VRM risks permanent breakdown due to lack of symmetrical avalanche structure.

What is the recommended PCB footprint for SMA4F70A according to ST's datasheet?

ST specifies an IPC7531-compliant SMA flat footprint with pad dimensions: 2.5 mm × 1.5 mm (length × width), 5.35 mm center-to-center spacing, and 0.5 mm solder mask clearance. Figure 13 in DS12542 Rev 1 shows exact dimensions in mm and inches, optimized for thermal dissipation and reflow yield using standard FR4 with 35 µm copper thickness.