The SMCJ33A-13: Its 33 V reverse standoff voltage (VRWM) means it sits across a 33 V rail without conducting leakage; clamping begins once the transient exceeds the 36.7 V minimum breakdown voltage. At the full 28.1 A peak pulse current (Ipp), the clamping voltage reaches 53.3 V maximum — this is the voltage the downstream circuitry must survive. The -55°C to 150°C junction temperature range covers both cold-start and hot-soak conditions in industrial and telecom enclosures.
The SMC footprint is larger than the SMA/SMB siblings — the extra copper pad area helps spread the thermal pulse from a 1500 W event into the PCB.
This is a standard catalog TVS, not a power-line protection device (the Power Line Protection flag is No), so it is intended for signal and DC rail transient suppression, not AC mains clamping.