What the 75V standoff and 5kW peak pulse rating mean for the protection circuit
The 5.0SMDJ75A-Q: 5000W peak pulse capacity is the relevant rating for specifying a TVS against real-world transients — automotive looms, relay kickback, and ESD events all present as short-duration, high-energy pulses; the 5kW figure tells you it survives a category of hits that would puncture a 400W part outright. Reverse standoff of 75V means the TVS sits invisible on the line under normal operation — the rail can swing up to 75V without drawing significant leakage current.