STMicroelectronics SM6T6V8A

Overview

SM6T6V8A from STMicroelectronics is a unidirectional transient voltage suppression (TVS) diode designed for primary-level ESD and surge protection on low-voltage signal and power lines. It features a 6.8 V nominal breakdown voltage (V_BR = 6.45 V min / 6.8 V typ), 10.5 V clamping voltage at 57 A (8/20 µs), 600 W peak pulse power (10/1000 µs), and ultra-low leakage current (≤0.2 µA at 25 °C). It is used in USB ports, sensor interfaces, and DC-DC converter input rails to prevent latch-up or permanent damage from IEC 61000-4-2 ±30 kV contact discharge events.

For engineers reviewing the SM6T6V8A datasheet, SM6T6V8A pinout, SM6T6V8A application, or SM6T6V8A equivalent, this page delivers verified electrical parameters, SMB package layout, real-world clamping behavior under 8/20 µs surges, thermal derating curves up to 150 °C junction temperature, and direct alternatives with documented V_BR, V_CL, and R_D differences.

Technical Context

The SM6T6V8A employs planar silicon avalanche technology to achieve precise, repeatable breakdown at 6.8 V with tight tolerance (±5% typical), enabling reliable overvoltage thresholding in 3.3 V and 5 V systems. Its dynamic resistance of 0.059 Ω (10/1000 µs) ensures minimal voltage overshoot during fast transients, while its 150 °C maximum junction temperature rating supports operation in thermally constrained industrial and automotive environments.

It complies with IEC 61000-4-2 Level 4 (±30 kV air/contact discharge), IEC 61000-4-4 Level 4 (4 kV), and UL497B recognition (file E136224) as an isolated loop circuit protector - confirming suitability for safety-critical telecom and industrial control interfaces without external isolation components.

Key Specifications

Pinout & Package

The SM6T6V8A is a two-terminal unidirectional TVS diode housed in an SMB (DO-214AA) surface-mount package with matte tin-plated leads. The cathode is marked by a band on the body; the anode is unmarked. The device operates with cathode connected to the protected line and anode to ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ6.8A and P6SMB6.8A, the SM6T6V8A delivers lower clamping voltage (10.5 V vs. ≥11.2 V) and superior high-temperature power retention (350 W at 150 °C vs. ≤300 W), making it optimal for thermally dense 3.3 V/5 V embedded systems where voltage margin and thermal headroom are constrained.

Availability

SM6T6V8A is available at Aetrix Electronics and suitable for USB interface protection, automotive sensor conditioning, industrial RS-485 port hardening, and DC-DC converter input surge suppression requiring stable component supply across multi-year production cycles.

Supply support for SM6T6V8A 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 microcontrollers, power devices, sensors, and protection ICs for automotive, industrial, and consumer markets.

The SM6T series belongs to ST's high-reliability TVS portfolio, engineered specifically for robust ESD/surge immunity in space-constrained, high-temperature applications such as automotive body electronics and industrial IoT edge nodes.

FAQ

What is the maximum clamping voltage of SM6T6V8A under a 57 A 8/20 µs surge?

The SM6T6V8A clamps to 10.5 V at 57 A for an 8/20 µs waveform, as specified in Table 2 of DS0684 Rev 15. This value is measured at T_amb = 25 °C and represents the peak voltage seen by downstream circuitry during worst-case surge conditions, ensuring compatibility with 3.3 V and 5 V logic families.

Can SM6T6V8A be used in bidirectional signal lines like RS-485?

No - SM6T6V8A is unidirectional and must be used with cathode toward the protected line. For bidirectional applications such as RS-485, the SM6T6V8CA variant (marked "LE") is required, which provides symmetrical clamping for both polarities and is validated per IEC 61000-4-4 common-mode testing.

Does SM6T6V8A meet UL497B requirements for isolated loop protection?

Yes - SM6T6V8A is UL497B recognized under file E136224 as an isolated loop circuit protector. This certification confirms its suitability for use in intrinsically safe barriers and hazardous-area signal conditioners without requiring additional isolation components in the protection path.

What is the thermal resistance junction-to-ambient for SM6T6V8A on a standard FR4 PCB?

On a recommended IPC-7531 footprint (2.07 mm × 5.84 mm copper pad per lead), the SM6T6V8A exhibits R_th(j-a) ≈ 120 °C/W for single-pulse operation, as shown in Figure 12 of DS0684. This value assumes 70 µm Cu thickness and no added thermal vias; adding two 0.3 mm vias per pad reduces R_th by ~35%.