AEC-Q101 TVS for 18 V automotive rails
The SMBJ18CAQ-13-F: The -55°C to 150°C junction temperature range covers under-hood and engine-bay thermal profiles, and the bidirectional topology means a single device protects both polarities on a signal or power line without a series diode.
Package and board-fit for DO-214AA SMB
The SMB footprint is smaller than the SMC package but still carries the full 600 W rating — the copper pad area under the cathode tab (in this bidirectional part, both terminals are interchangeable) sets the thermal resistance to the board.