110V rail clamp — what the ratings mean
The reverse standoff voltage is 110V, meaning the device does not conduct at normal rail voltage — it only starts clamping when the transient exceeds the breakdown threshold. The minimum breakdown voltage is 122V, so the rail must stay below that to avoid leakage.
500W pulse — sizing for the transient
That 500W is the product of the clamping voltage and the peak current — at 196V clamp, the device handles 2.6A for that pulse width. For shorter transients (e.g. 8/20 µs), the peak current capability is higher, but the datasheet's derating curve must be followed. The 500W rating is the absolute maximum at 25°C; derate linearly above that per the datasheet.
That saves a diode in the bill of materials compared to using two unidirectional TVS devices back-to-back. The breakdown and clamping voltages are the same for both polarities.
DO-214AC SMA — footprint and temperature range
Housed in the standard DO-214AC (SMA) package, surface-mount.
Microchip lists this part as Active. The part ships on Tape & Reel.