STMicroelectronics SM6T100A

Overview

SM6T100A from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode in SMB package, designed for IEC 61000-4-2 ESD protection and IEC 61000-4-4 surge suppression on signal/power lines. It features 100 V standoff voltage (VRM), 137 V clamping voltage at 4.4 A (8/20 µs), 600 W peak pulse power (10/1000 µs), and operates up to 150 °C junction temperature - deployed in industrial power supplies and telecom interface protection.

For engineers reviewing the SM6T100A datasheet, SM6T100A pinout, SM6T100A application, or SM6T100A equivalent, this page delivers verified electrical parameters, SMB package layout, real-world clamping behavior, thermal derating curves, and validated alternatives for overvoltage protection design in high-reliability DC power rails and data line interfaces.

Technical Context

The SM6T100A uses planar silicon junction technology to achieve low leakage (0.2 µA @ 25 °C, 1 µA @ 85 °C) and stable breakdown characteristics across -55 °C to +150 °C operating range. Its unidirectional configuration provides asymmetric clamping - forward conduction during positive transients, reverse blocking until breakdown at 100 V nominal V_BR.

Clamping performance is defined by dynamic resistance (R_D = 3.24 Ω) and temperature coefficient α_T = 10.6 × 10⁻⁴/°C, enabling accurate V_CL prediction across junction temperature. It meets IEC 61000-4-2 Level 4 (30 kV air/contact discharge) and UL497B recognition (E136224) as an isolated loop circuit protector.

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 J-STD-002 and JEDEC MO-136.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ100A and P6SMB100A, SM6T100A offers tighter V_BR tolerance (85.5–105 V vs. 90–111 V), lower dynamic resistance (3.24 Ω vs. ≥4.1 Ω), and superior high-temperature leakage stability - making it preferred for precision clamping in thermally demanding industrial power designs.

Availability

SM6T100A is available at Aetrix Electronics and suitable for industrial power supply input protection, telecom line interface protection, automotive body control module power rails, and smart meter auxiliary supply designs requiring stable component supply and full compliance with IEC 61000-4-2/4-4 and UL497B.

Supply support for SM6T100A 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, designing and manufacturing analog, microcontroller, power, and sensing solutions for industrial, automotive, and consumer markets.

The SM6T series belongs to ST's transient protection portfolio, engineered specifically for high-reliability, low-leakage ESD and surge suppression in space-constrained SMB layouts - targeting applications where thermal stability and long-term parametric consistency are critical.

FAQ

What is the maximum clamping voltage of SM6T100A under IEC 61000-4-4 4 kV surge conditions?

The SM6T100A clamps to 137 V at 4.4 A for an 8/20 µs waveform, which corresponds to the IEC 61000-4-4 Level 4 (4 kV) test condition. This value is measured at T_j = 25 °C; actual V_CL increases linearly with junction temperature using α_T = 10.6 × 10⁻⁴/°C.

Can SM6T100A be used in bidirectional signal line protection?

No - SM6T100A is unidirectional and only clamps positive transients on the cathode side. For bidirectional protection (e.g., RS-485, USB D+/D−), SM6T100CA must be used, which has symmetrical breakdown in both directions and identical V_RM/V_CL ratings.

Does SM6T100A require derating at elevated ambient temperatures?

Yes - its peak pulse power drops from 600 W at 25 °C to 350 W at T_j = 150 °C (Figure 3). Derating must account for PCB copper area (R_th(j-a) improves from 140 °C/W to 60 °C/W with 4 cm² copper per lead) and thermal impedance Z_th(j-a) versus pulse duration.

Is SM6T100A compliant with RoHS and REACH environmental directives?

Yes - SM6T100A is manufactured in ST's ECOPACK2-compliant SMB package, meeting RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006, with lead-free matte tin plating and halogen-free molding compound per ST's published environmental documentation.