It is rated for 400 W peak pulse power and clamps at 25.3 V maximum, with a breakdown voltage window starting at 13.3 V.
The 12 V reverse standoff voltage is the maximum DC voltage the device can withstand without conducting — it sits on the rail and only acts when a transient exceeds the 13.3 V breakdown threshold.
Clamping voltage and peak pulse current
When a transient hits, the SM4T14AY clamps at 25.3 V maximum while shunting up to 91 A (8/20 µs waveform). The 400 W rating is the peak pulse power — enough for typical automotive load-dump and inductive kickback events.
Package and footprint: DO-214AC (SMA)
The supplier device package is SMA. Mounting is surface mount.