The STMicroelectronics SM15T22AY is a 1500W peak pulse power Zener TVS diode designed for automotive transient protection. It is AEC-Q101 qualified, confirming its suitability for stress-prone environments like engine control units, transmission controllers, and body electronics where load-dump and inductive-load transients are a daily reality.
On a 24V automotive system, the 18.8V standoff means the diode stays out of conduction during normal operation, but when a load-dump or alternator field-decay event pushes the bus above 20.9V (the minimum breakdown voltage), the device starts conducting and holds the clamp at 39.3V maximum. The 254A peak pulse current rating (8/20µs waveform) tells you it can handle the high-current, short-duration spikes typical of ISO 7637-2 pulses without exceeding the junction temperature limit.
Package and mounting — SMC footprint for production
The SM15T22AY comes in the DO-214AB (SMC) package, a surface-mount body that fits standard reflow processes. The SMC footprint is larger than the smaller SMA/SMB packages, which helps with thermal dissipation during the surge event — the 1500W pulse generates heat that the package must sink into the PCB copper.