STMicroelectronics SM6T30A

Overview

SM6T30A from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode in SMB package, designed to clamp transient overvoltages up to 41.5 V at 14.5 A (10/1000 µs), with 600 W peak pulse power rating and 0.2 µA max leakage at 25 °C. It protects MOSFETs, ICs, and signal lines against IEC 61000-4-2 ESD (±30 kV contact/air) and IEC 61000-4-4 fast transients (4 kV) in industrial power supplies and automotive control modules.

For engineers reviewing the SM6T30A datasheet, SM6T30A pinout, SM6T30A application, or SM6T30A equivalent, this device is selected for high-reliability surge protection where low leakage, stable clamping voltage (V_CL = 41.5 V), junction temperature resilience (T_j up to 150 °C), and SMB footprint compatibility are critical in space-constrained PCB layouts.

Technical Context

The SM6T30A operates as a silicon avalanche diode with planar junction technology, enabling precise breakdown voltage (V_BR = 25.6–31.5 V) and low dynamic resistance (R_D = 0.69 Ω at 25 °C). Its clamping behavior follows V_CL = V_BR(max) + R_D × I_PP, delivering predictable voltage limiting during 8/20 µs surges up to 75 A.

It complies with UL497B (file E136224) as an isolated loop circuit protector and meets IEC 61000-4-2 Level 4 (±30 kV) and IEC 61000-4-4 Level 4 (4 kV), with thermal performance validated per JESD22-B102 E3 and JEDEC registered SMB outline.

Key Specifications

Pinout & Package

SMB (DO-214AA) surface-mount package: 3.3–3.95 mm length, 5.1–5.6 mm width, 1.9–2.45 mm height, matte tin-plated leads compliant with IPC7531 footprint and J-STD-020 MSL level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ30A and P6SMB30A, SM6T30A offers the lowest clamping voltage (41.5 V) among SMB 600 W TVS diodes at its standoff rating, enabling tighter protection margins for 24 V industrial buses and improved reliability in high-temperature ambient conditions due to superior thermal derating.

Availability

SM6T30A is available at Aetrix Electronics and suitable for industrial motor drives, automotive body control modules, and AC-DC SMPS secondary-side protection requiring stable component supply and full traceability.

Supply support for SM6T30A 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 automotive-grade ICs with vertical manufacturing and broad industrial qualification.

The SM6T series belongs to ST's transient protection portfolio, engineered specifically for high-reliability industrial and automotive applications demanding low-leakage, high-temperature stability, and certified surge immunity in compact SMB packages.

FAQ

What is the maximum clamping voltage of SM6T30A under a 10/1000 µs surge?

The maximum clamping voltage (V_CL) is 41.5 V at 14.5 A for a 10/1000 µs waveform, measured at T_amb = 25 °C. This value increases with junction temperature per the coefficient α_T = 9.7 × 10⁻⁴/°C, reaching ~45.2 V at T_j = 125 °C using V_CL(T_j) = V_CL(25 °C) × [1 + α_T × (T_j − 25)].

Can SM6T30A be used in bidirectional signal lines like RS-485?

No - SM6T30A is unidirectional and conducts only in reverse bias; it cannot clamp positive transients on bidirectional lines. For RS-485, the bidirectional variant SM6T30CA must be used, which provides symmetrical clamping (±41.5 V) and identical electrical specs except for polarity.

Does SM6T30A meet automotive AEC-Q200 requirements?

SM6T30A is not AEC-Q200 qualified. While it operates up to 150 °C and meets IEC/UL standards for industrial use, ST does not list it in their AEC-Q200 stress-tested portfolio. For automotive-critical applications, consider ST's AEC-Q200-qualified SMAJ or SMCJ series instead.

What is the recommended PCB footprint for SM6T30A?

The JEDEC-registered SMB footprint requires pad dimensions of 1.62 mm × 2.60 mm (anode/cathode), 5.84 mm center-to-center spacing, and 2.07 mm width for solder mask defined pads. Copper area under each lead should exceed 1 cm² to achieve R_th(j-a) ≤ 120 °C/W per Figure 12 in DS0684 Rev 15.