12V rail protection in a DO-214AC SMA package
It offers a reverse standoff voltage of 12V, a minimum breakdown voltage of 13.3V, and a maximum clamping voltage of 25.3V at the peak pulse current of 91A (8/20 µs waveform).
This is a standard catalog part from STMicroelectronics, widely available through distribution channels.
What the clamping and breakdown voltages mean for your rail
The 12V reverse standoff voltage means the diode will not conduct appreciably below 12V, so it sits across a 12V supply without loading it. The 13.3V minimum breakdown ensures the device starts clamping before the rail exceeds safe levels. The 25.3V maximum clamping at 91A is the worst-case voltage the protected circuitry sees during a surge — ensure downstream components are rated above this level. The 400W peak pulse power (8/20 µs) defines the energy the diode can absorb in a single transient event; for repetitive surges or longer pulse widths, derate accordingly.