Protection window and clamping behaviour
The 1.5SMC120CA M6G: The 165 V clamp ceiling means downstream semiconductors rated for 200 V or more have adequate headroom. The junction temperature rating is the same as the ambient limit — no derating needed for continuous DC bias at high ambient.
Package, mounting and production status
Taiwan Semiconductor lists this part as Active in production. The device is classified as General Purpose for applications — suitable for DC rail clamping, I/O line protection, and secondary surge suppression in power supplies and industrial control boards.