What the 12V standoff and 100W rating mean on the board
The SMF12CT1G is a 5-channel unidirectional Zener TVS array from onsemi, rated for a 12V reverse standoff voltage and a peak pulse power of 100W. The 12V standoff means this part sits on a 12V rail and will not conduct until the transient exceeds 13.3V breakdown — it stays invisible to the circuit during normal operation. The 100W peak pulse rating (with a 6A peak pulse current per the 8/20µs waveform) tells you it can absorb a moderate ESD or surge event without failing short; it is not built for lightning-level transients on a mains-fed line. With five unidirectional channels in a single SC-88 (SOT-363) package, this array protects five separate signal or power lines against overvoltage events. The 40pF capacitance per channel at 1MHz means it loads high-speed data lines minimally — suitable for USB 2.0, 10/100 Ethernet, or general-purpose I/O where signal rise time matters.