1.5 kW bidirectional TVS for 40 V automotive rails
The STMicroelectronics SM15T47CAY is a bidirectional Zener-type transient voltage suppressor from the SM15TY TRANSIL™ series, rated for 1.5 kW peak pulse power (10/1000 µs waveform) and qualified to AEC-Q101. It clamps transients to 84 V maximum at the rated peak pulse current of 119 A (8/20 µs waveform), with a reverse standoff voltage of 40.2 V and a minimum breakdown voltage of 44.7 V.
The 84 V maximum clamping voltage at 119 A (8/20 µs) is the ceiling the downstream circuitry sees during a surge event. For a 40 V nominal rail, that leaves roughly 44 V of headroom to the typical 60 V or 80 V breakdown of downstream switching regulators or load switches. The 44.7 V minimum breakdown ensures the TVS does not conduct during normal operation on a 40.2 V standoff rail, but starts clamping before the rail exceeds the downstream device's absolute maximum. The 1.5 kW pulse rating means it can absorb a single 8/20 µs surge of that energy without failing short — a common requirement for automotive load-dump and ISO 7637-2 pulse coordination.
AEC-Q101 and the automotive bill of materials
For a buyer filling a BOM line, this part is specified into the automotive ECU or module without a near-term obsolescence risk. The SM15TY series is a standard ST product line, so second-source options from other AEC-Q101 TVS families exist (e.g., Littelfuse, Vishay, Onsemi) but pin-for-pin compatibility must be verified against the DO-214AB footprint and the specific breakdown voltage bin.
Sourcing and quoting for production
The DO-214AB package is a standard SMC footprint, compatible with common reflow profiles. The part is RoHS compliant per the TRANSIL series designation.