The SMCJ120A-13-F: The 120 V reverse standoff voltage means the diode draws negligible leakage below that rail level, so it sits across a 120 V bus without loading it. Breakdown occurs at a minimum of 133 V, and the clamping voltage is held to 193 V maximum at the 7.9 A peak pulse current.
Package and board-fit for the SMC footprint
Housed in the DO-214AB (SMC) package, a standard surface-mount footprint for TVS diodes rated above 1 kW. The large copper tab on the bottom side conducts heat into the PCB pad — the board copper area under the package sets the effective thermal resistance for repetitive surge duty. Rated for operation from -55°C to +150°C junction, covering the full industrial temperature range and most automotive under-hood environments where the ambient near the PCB can exceed 105°C. The wide-temperature spec is typical of a Zener-based TVS structure that maintains stable breakdown voltage across the thermal envelope.