What the clamping ratings mean for your rail
The 1.5SMC75A-M3/9AT: Once triggered, the clamping ceiling is 104 V max at the rated peak pulse current of 14.6 A (10/1000 µs waveform), which limits what reaches the downstream circuitry to a defined let-through voltage rather than the raw transient. 1500 W peak pulse capacity at the 10/1000 µs standard surge shape means this part handles the duration and energy level typical for AC-line and DC-bus transient events in industrial equipment — not the longer-duration inductive kick that demands a higher-energy part. The thermal junction limit is 150°C, so the board-level heatsinking path and local ambient define how many repeated transients the part absorbs before its junction temperature budget is exhausted.
DO-214AB SMC footprint and assembly context
The DO-214AB (SMCJ) package ships in Tape & Reel — the cathode band marks the unidirectional polarity direction, which must align with the protected rail on the PCB.