STMicroelectronics SM30T47AY

Overview

SM30T47AY from STMicroelectronics is a unidirectional automotive-grade transient voltage suppression (TVS) diode designed for ISO 7637-2 pulse protection in 12 V/24 V vehicle power networks. It delivers 3000 W peak pulse power (10/1000 µs), clamps at 64.5 V (max) under 43.5 A surge, and operates up to 175 °C junction temperature - deployed in engine control units, body control modules, and infotainment power rails.

For engineers reviewing the SM30T47AY datasheet, SM30T47AY pinout, SM30T47AY application, or SM30T47AY equivalent, key selection criteria include its 46.7 V nominal breakdown voltage, low 0.2 µA leakage at 25 °C, SMC package compatibility with IPC7531 footprint, and AEC-Q101 qualification for under-hood reliability.

Technical Context

This TVS diode uses planar silicon technology to achieve stable high-temperature operation (Tj up to 175 °C) and ultra-low leakage (≤0.2 µA at VRM), critical for long-term stability in automotive electronics exposed to thermal cycling. Its unidirectional configuration enables asymmetric surge suppression on positive-rail circuits without reverse conduction path concerns.

The device meets stringent automotive immunity standards: ISO 10605 ESD (±30 kV air/contact), IEC 61000-4-4 EFT Level 4 (4 kV), and ISO 7637-2 transients including Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V) - all verified per DS8599 Rev 13.

Key Specifications

Pinout & Package

SM30T47AY is housed in an industry-standard SMC (DO-214AB) surface-mount package with JEDEC-registered outline, matte tin-plated leads, and IPC7531-compliant footprint. The two-terminal device has no polarity marking on cathode; orientation follows standard SMC convention (cathode band at one end).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ48A and 1.5KE47A, SM30T47AY provides 7.5× higher peak power, 12.9 V lower clamping at rated current, AEC-Q101 assurance, and validated ISO 7637-2 performance - making it the sole choice for new automotive power rail protection where reliability and space-constrained SMC mounting are mandatory.

Availability

SM30T47AY is available at Aetrix Electronics and suitable for engine control units, body control modules, and infotainment head units requiring stable component supply across extended automotive production lifecycles.

Supply support for SM30T47AY 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 solutions with vertical manufacturing and broad IP portfolio.

SM30T47AY belongs to the SM30TY series - a family of AEC-Q101-qualified, high-power TVS diodes engineered specifically for robust transient suppression in 12 V/24 V automotive power networks per ISO 7637-2 and ISO 10605.

FAQ

What is the maximum clamping voltage of SM30T47AY under a 10/1000 µs surge?

The maximum clamping voltage (VCL) is 64.5 V at 43.5 A for a 10/1000 µs waveform, measured at 25 °C ambient per DS8599 Rev 13 Table 2. This value increases with junction temperature due to the αT coefficient (10.1 × 10⁻⁴/°C), reaching ~67.2 V at 125 °C.

Is SM30T47AY suitable for bidirectional signal line protection?

No - SM30T47AY is unidirectional and intended only for DC power rail protection. For bidirectional signal lines (e.g., CAN, LIN, USB), ST offers the SM30T47CAY variant, which features symmetrical breakdown in both polarities and is marked "3BARY" per Table 6.

Does SM30T47AY require a heatsink for 3000 W surge handling?

No external heatsink is required for single-event surge handling. The SMC package achieves sufficient thermal dissipation via PCB copper area (Figure 12 shows Rth(j-a) ≤ 4.5 °C/W with 5 cm² copper per lead). Continuous power dissipation remains negligible due to TVS's transient-only operation.

How does SM30T47AY compare to SM30T42AY in terms of voltage margin for a 48 V system?

SM30T47AY (VBR = 44.4–49.0 V) provides tighter margin above 42 V nominal systems than SM30T42AY (VBR = 40.0–44.2 V), reducing risk of premature conduction during normal 48 V battery float (up to 54 V). Its higher VCL (64.5 V vs. 58.1 V) also allows safer interface with 65 V-rated downstream components.