STMicroelectronics SMA6T56AY

Overview

SMA6T56AY from STMicroelectronics is a unidirectional 600 W automotive-grade transient voltage suppressor (TVS) diode designed for ISO 7637-2 pulse protection in 12 V/24 V vehicle power networks. It features a 56 V breakdown voltage (V_BR = 56.0 V), clamps to ≤76.6 V at 7.8 A (10/1000 µs), and operates up to +150 °C junction temperature - enabling robust surge suppression in engine control units, body electronics, and infotainment power rails.

For engineers reviewing the SMA6T56AY datasheet, SMA6T56AY pinout, SMA6T56AY application, or SMA6T56AY equivalent, key selection criteria include its AEC-Q101 qualification, low leakage (≤0.2 µA @ 25 °C), JEDEC DO-214AC (SMA) package compatibility, and verified performance against ISO 10605 (±30 kV ESD) and ISO 7637-2 pulses (Pulse 1: −150 V, Pulse 2a: +112 V, Pulse 3a: −220 V).

Technical Context

The SMA6T56AY implements a planar silicon avalanche structure optimized for fast response (<1 ns) to transients while maintaining low dynamic resistance (R_D = 1.03 Ω) and stable clamping under repeated surges. Its unidirectional polarity enables DC-biased rail protection without reverse conduction during normal operation.

It meets stringent automotive reliability requirements: AEC-Q101 qualification, MSL Level 1 moisture sensitivity, JESD201 Class 2 whisker resistance, and UL94 V0 flammability rating - all validated across −55 °C to +150 °C operating range with no derating required up to T_j = 150 °C.

Key Specifications

Pinout & Package

Manufactured in JEDEC DO-214AC (SMA) package: surface-mount, single-row, two-terminal configuration with matte tin-plated leads. Dimensions per DS6931 Rev 9: D = 2.25–2.90 mm, E = 4.80–5.35 mm, L = 0.75–1.50 mm, weight = 0.072 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMA6T56A and SMCJ56A, the SMA6T56AY delivers certified automotive reliability in the smallest qualified footprint, balancing surge margin, leakage, and thermal capability without compromising AEC-Q101 compliance or board space.

Availability

SMA6T56AY is available at Aetrix Electronics and suitable for engine control units, body electronics modules, infotainment systems, and ADAS camera power supplies requiring stable component supply across extended automotive lifecycles.

Supply support for SMA6T56AY 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, MCU, power, and automotive ICs with vertical fabrication capabilities.

The SMA6TY series belongs to ST's Transil™ TVS portfolio, engineered specifically for AEC-Q101-compliant transient protection in 12 V/24 V automotive power networks - emphasizing low leakage, high-temperature stability, and ISO standard compliance.

FAQ

What is the maximum clamping voltage of SMA6T56AY under a 10/1000 µs surge?

The maximum clamping voltage (V_CL) is 76.6 V at 7.8 A peak pulse current (I_PP) for a 10/1000 µs waveform, measured at T_j = 25 °C. This value increases with junction temperature per α_T = 10 × 10⁻⁴/°C, reaching ~82.5 V at T_j = 150 °C using the formula V_CL(T_j) = V_CL(25 °C) × [1 + α_T × (T_j − 25)].

Is SMA6T56AY bidirectional or unidirectional?

SMA6T56AY is unidirectional: it conducts only during positive overvoltage events on the cathode relative to anode. Its marking "6USY" (per Table 6) and designation "AY" (not "CAY") confirm unidirectional polarity. Bidirectional variants carry "CAY" suffix (e.g., SMA6T56CAY) and exhibit symmetrical clamping in both polarities.

Does SMA6T56AY meet ISO 7637-2 Pulse 3a requirements?

Yes - SMA6T56AY is characterized to withstand ISO 7637-2 Pulse 3a (−220 V, 50 Ω source, 15 ms duration) with clamping below 110 V, as confirmed by Figure 15 in DS6931 Rev 9. Its 600 W rating and low R_D ensure energy absorption without thermal runaway during this fast, high-current transient.

What is the recommended PCB footprint for SMA6T56AY?

The recommended footprint follows JEDEC DO-214AC (SMA) standards per Figure 18 in DS6931 Rev 9: pad length = 5.43 mm (2.63 mm solder mask opening), pad width = 1.40 mm, center-to-center spacing = 3.90–4.10 mm. Copper area under each lead should be ≥1 cm² to maintain R_th(j-a) ≤ 4.5 °C/W and prevent thermal saturation during repetitive surges.