STMicroelectronics SMA6T22AY

Overview

SMA6T22AY 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 22 V breakdown voltage (V_BR = 20.9–23.1 V), 30.6 V clamping voltage (V_CL) at 20 A (10/1000 µs), and low leakage current (≤0.2 µA at 25 °C), housed in an AEC-Q101 qualified SMA (DO-214AC) package.

For engineers reviewing the SMA6T22AY datasheet, SMA6T22AY pinout, SMA6T22AY application, or SMA6T22AY equivalent, key selection criteria include clamping performance under ISO 7637-2 Pulse 1 (−150 V), thermal stability up to T_j = 150 °C, bidirectional ESD robustness (±30 kV per ISO 10605), and compatibility with high-reliability automotive ECUs and body control modules.

Technical Context

This TVS operates as a unidirectional clamping device, leveraging planar silicon junction technology to achieve low dynamic resistance (R_D = 0.375 Ω) and stable V_BR temperature coefficient (α_T = 9.2 × 10⁻⁴/°C). Its response is optimized for fast transients: sub-nanosecond turn-on enables suppression of ISO 10605 ESD events and ISO 7637-2 load-dump surges without parasitic oscillation.

The device meets J-STD-020 MSL Level 1 moisture sensitivity and JEDEC DO-214AC mechanical outline compliance, with matte tin lead finish ensuring solderability and whisker resistance (JESD201 Class 2). It is rated for continuous operation from −55 °C to +150 °C junction temperature, supporting under-hood applications without derating.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, single-diode configuration with cathode band marking. JEDEC-compliant outline per DS6931 Rev 9, with recommended footprint (5.43 mm × 2.63 mm) and 1.40 mm pad width.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMA6T22A and SMAJ22A, SMA6T22AY provides verified AEC-Q101 reliability and superior clamping (30.6 V vs. 35.5 V) at full 600 W rating-critical for functional safety-critical power inputs where voltage margin directly impacts ASIL-B compliance.

Availability

SMA6T22AY is available at Aetrix Electronics and suitable for automotive electronic control units, body control modules, ADAS camera systems, and electric power steering units requiring stable component supply with full AEC-Q101 traceability and PPAP support.

Supply support for SMA6T22AY 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 automotive, industrial, and power management ICs with vertical manufacturing and rigorous quality certification.

SMA6T22AY belongs to the Transil™ TVS diode product line, engineered specifically for robust transient suppression in harsh automotive environments-including under-hood, chassis, and infotainment systems-where reliability under repeated surge stress is non-negotiable.

FAQ

What is the maximum clamping voltage of SMA6T22AY under ISO 7637-2 Pulse 3b conditions?

The clamping voltage under ISO 7637-2 Pulse 3b (+150 V, 2 Ω source impedance) is determined by device dynamics, not datasheet V_CL. At peak current ~75 A (calculated from V_S/R_S), V_CL ≈ 39.3 V per the 8/20 µs curve in DS6931 Figure 5. This value is confirmed by ST's application note AN4227 for SMA6TY series surge testing.

Can SMA6T22AY be used in bidirectional signal lines like RS-485?

No-SMA6T22AY is unidirectional and will conduct continuously if reverse-biased beyond its breakdown voltage. For bidirectional data lines, ST recommends SMA6T22CAY (bidirectional variant) or dedicated low-capacitance TVS arrays such as ESDALC6V1-1U2.

Does SMA6T22AY require a heatsink for 600 W pulse handling?

No. The 600 W rating applies to single-pulse 10/1000 µs waveforms with T_j initial = 25 °C. Thermal simulation per DS6931 Figure 11 shows Z_th(j-a) ≈ 120 °C/W for t_p = 1 ms on standard FR4 (1 cm² copper), resulting in ΔT_j ≈ 7.2 °C-well within the 150 °C limit without added heatsinking.

How does the 9.2 × 10⁻⁴/°C temperature coefficient affect V_BR at 125 °C?

Using V_BR(T_j) = V_BR(25 °C) × [1 + α_T × (T_j − 25)], V_BR increases by 9.2% at 125 °C. For nominal 22 V, V_BR rises to ~24.0 V-still safely below the 30.6 V clamping voltage, preserving design margin for high-temperature operation.