Transient voltage suppressor for 150 V rail protection
The 1.5SMC180CA_R1_00001: The 154 V standoff means the diode draws negligible leakage below that level, so it sits across a 150 V nominal bus without loading it during normal operation.
Clamping voltage and breakdown margin for the BOM
Minimum breakdown voltage is 171 V, giving a 17 V margin above the 154 V standoff before the diode starts conducting significantly. The 246 V maximum clamping voltage at 6.1 A peak pulse current sets the upper bound the downstream circuitry must survive — any device rated below 250 V on that node needs additional protection or a higher-rated TVS.