1.5 kW peak pulse — what the ratings mean for the protected rail
The SMCJ17CA-13-F: The 17 V reverse standoff voltage means the diode stays transparent on a nominal 12 V or 15 V rail, and the 18.9 V minimum breakdown threshold ensures it begins conducting before the downstream circuitry sees an overvoltage event.
Bidirectional Zener — single-channel protection
A single bidirectional channel (Zener-type TVS) protects signal or power lines against both positive and negative transients without needing a series diode pair.