Vishay General Semiconductor - Diodes Division SM6T39CAHE3_A/I

Overview

SM6T39CAHE3_A/I from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMB (DO-214AA) package, rated for 39 V breakdown voltage (V_BR = 37.1–41.0 V at 1.0 mA), 600 W peak pulse power (10/1000 μs), 53.9 V maximum clamping voltage at 11.1 A, and AEC-Q101 qualified for automotive use. It protects signal lines and MOSFET gates in sensor units and power electronics against inductive switching transients.

For engineers reviewing the SM6T39CAHE3_A/I datasheet, SM6T39CAHE3_A/I pinout, SM6T39CAHE3_A/I application, or SM6T39CAHE3_A/I equivalent, key selection criteria include bidirectional clamping capability, low clamping ratio (1.38), RoHS-compliant + halogen-free construction, and MSL Level 1 reflow compatibility up to 260 °C.

Technical Context

This bidirectional TVS operates symmetrically across both polarities, with identical V_BR, V_C, and I_PPM specifications in forward and reverse directions. Its glass-passivated junction ensures stable leakage (<1.0 μA at 33.3 V) and robust surge handling under repetitive transients.

Designed for surface-mount automated placement, the device uses matte tin-plated leads compliant with J-STD-002 and JESD 22-B102, and achieves thermal resistance of 100 °C/W (junction-to-ambient) on standard 5.0 mm × 5.0 mm copper pads.

Key Specifications

Pinout & Package

Package: SMB (DO-214AA), surface-mount, low-profile case with matte tin-plated leads; meets UL 94 V-0 flammability rating and JESD 201 Class 2 whisker resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ39CA and TPSMA6V8A, SM6T39CAHE3_A/I uniquely combines bidirectional operation, 33.3 V stand-off, AEC-Q101 qualification, and 10/1000 μs waveform optimization-making it optimal for automotive sensor interfaces and industrial 24 V control systems where polarity-agnostic clamping and automotive reliability are mandatory.

Availability

SM6T39CAHE3_A/I is available at Aetrix Electronics and suitable for automotive sensor protection, industrial PLC I/O hardening, and telecom line interface designs requiring stable component supply, long-term lifecycle support, and traceable AEC-Q101 qualified parts.

Supply support for SM6T39CAHE3_A/I 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

Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, rectifiers, MOSFETs, and protection devices with emphasis on reliability, efficiency, and application-specific performance.

The SM6T Series is engineered for robust transient suppression in harsh environments, targeting automotive, industrial, and telecom applications where high pulse power, low clamping, and qualification-grade consistency are critical.

FAQ

What is the clamping voltage of SM6T39CAHE3_A/I at its rated peak pulse current?

The SM6T39CAHE3_A/I has a maximum clamping voltage (V_C) of 53.9 V at 11.1 A peak pulse current using the industry-standard 10/1000 μs waveform. This value is measured under specified test conditions per JEDEC standards and reflects worst-case voltage seen by protected circuitry during surge events. The clamping performance is consistent in both directions due to its bidirectional design, and SM6T39CAHE3_A/I maintains this specification across its full operating temperature range of -65 °C to +150 °C.

Is SM6T39CAHE3_A/I suitable for automotive applications?

Yes, SM6T39CAHE3_A/I is explicitly AEC-Q101 qualified, as confirmed by Vishay's ordering code suffix "HE3" and documentation revision 09-Jan-2024. It undergoes rigorous stress testing-including temperature cycling, highly accelerated life testing (HALT), and ESD validation-to meet automotive reliability requirements. SM6T39CAHE3_A/I is commonly deployed in engine control units, body electronics, and ADAS sensor modules where immunity to load dump and jump-start transients is essential.

What does the "CA" suffix indicate in SM6T39CAHE3_A/I?

The "CA" suffix in SM6T39CAHE3_A/I denotes a bidirectional configuration, meaning the device provides symmetrical transient suppression in both forward and reverse polarities. Unlike unidirectional variants (e.g., SM6T39A), SM6T39CAHE3_A/I has no cathode marking and functions identically regardless of terminal orientation. This eliminates polarity-dependent layout errors and simplifies design for AC-coupled or differential interfaces where voltage transients may swing above or below ground.

What is the thermal resistance of SM6T39CAHE3_A/I, and how does it affect PCB layout?

SM6T39CAHE3_A/I has a typical junction-to-ambient thermal resistance (R_θJA) of 100 °C/W when mounted on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes standard FR-4 board material and no internal copper planes. To maintain safe junction temperatures under repeated surges, designers must provide adequate copper area and avoid excessive trace length. SM6T39CAHE3_A/I's R_θJL of 20 °C/W indicates efficient heat conduction to solder joints, supporting reliable operation even in thermally constrained layouts.

Does SM6T39CAHE3_A/I require derating at elevated ambient temperatures?

Yes, SM6T39CAHE3_A/I must be derated above 25 °C ambient per Figure 2 in Vishay document 88385. At 85 °C ambient, its peak pulse power capability drops to approximately 420 W (70% of 600 W), and at 125 °C, it falls to ~240 W (40%). Derating applies to both single-pulse and repetitive surge conditions. SM6T39CAHE3_A/I's thermal characteristics ensure continued functionality within its -65 °C to +150 °C junction temperature range, but sustained high-temperature operation requires careful thermal design and surge duty cycle management.