Protection ratings and what they mean for the rail
The 1.5SMC440A: The 2.5 A peak pulse current at the clamping voltage confirms the diode can handle a 602 V, 2.5 A event without failing short — useful for sizing the upstream fuse or PTC to coordinate the protection chain.
Temperature grade and environment
A TVS in an outdoor telecom cabinet or an unheated enclosure sees the same derating curve; no mid-range temperature bin to track.
