What the ratings mean for the BOM
The 1.5SMC100: That rating tells you the device absorbs a defined energy pulse without failing short; it does not tell you the steady-state dissipation, which is near zero for a TVS. The 85.5 V reverse standoff voltage (working voltage) means the TVS draws negligible leakage below that rail. The 90 V minimum breakdown guarantees the clamping starts above the normal operating voltage. The 143.85 V maximum clamp at 11.1 A peak pulse current sets the voltage the downstream ICs must survive.
Board-fit and package note
DO-214AB (SMC) is the larger of the standard SMC package variants — the same footprint as the SMCJ suffix in the supplier device package field. The 1500 W rating requires the larger body to dissipate the pulse energy; a DO-214AA (SMA) package in the same series would be limited to 600 W. The cathode band on the body marks the unidirectional orientation — reverse the part and the TVS acts as a forward-biased diode, clamping at about 1 V instead of 143 V, which destroys the protection function.
Lifecycle reality — obsolete with no successor on record
Littelfuse has marked the 1.5SMC100 as obsolete.