What the ratings mean on the bench
The SMBJ100A-13: That 600 W rating means it can absorb a 3.7 A pulse before the junction temperature climbs past the 150 °C absolute maximum. The 100 V reverse standoff voltage is the DC rail level it protects without conducting leakage. Breakdown starts at 111 V minimum, and the clamping voltage at peak current is 162 V maximum — so a 100 V bus sees the diode clamp transients to 162 V, which is the voltage the downstream silicon must survive. The package is DO-214AA (SMB), a surface-mount footprint that reflows on a standard 260 °C profile.
Active production — sourcing posture
Pricing and current availability are confirmed at quote time against the BOM quantity.
Single-channel unidirectional — fit check
This is a unidirectional TVS with one channel, so it protects a single DC rail against positive-going transients relative to ground. For AC lines or bidirectional protection, a different part in the SMBJ family (the 'CA' suffix) would be the correct choice. The DO-214AA SMB package has a standard anode/cathode marking — the cathode band aligns with the protected rail, anode to ground. The 600 W rating assumes a minimum copper pad area per the datasheet layout recommendation; a smaller pad increases thermal resistance and reduces the effective pulse capability.