Littelfuse has marked the 1.5SMC120C as obsolete. If your BOM still calls out this exact order code, the supply path is broker-sourced inventory, not factory-direct.
Clamping performance and protection envelope
The reverse standoff voltage is 102 V, meaning the diode stays transparent on a 100 V rail and only begins clamping above the 108 V breakdown minimum. This is a single-channel bidirectional Zener TVS — it protects against both positive and negative transients on the same line, which simplifies layout for AC-coupled or differential signal pairs.
Housed in a DO-214AB (SMC) surface-mount package, the same footprint as the SMCJ series. The 1500 W rating in this package demands a good thermal connection to the PCB copper — the cathode tab is the primary heat path.