Surge rating and protection window
The SMCJ120CA-13: The 120 V reverse standoff voltage means it stays off the bus under normal conditions, only conducting when the line exceeds 133 V (minimum breakdown). The single bidirectional channel protects both polarities of a signal or low-voltage DC bus in a single package — useful for AC-coupled lines or bipolar supplies where two unidirectional devices would otherwise be needed.
Package and thermal envelope
Housed in the DO-214AB (SMC) surface-mount package, the SMCJ120CA-13 is a standard footprint for 1.5 kW-class TVS diodes.
Application fit and sourcing posture
Marked for General Purpose use, this TVS is suited for transient suppression on DC power rails, signal lines, and I/O ports where 120 V nominal operation is present. It is not intended for AC mains power line protection — the Power Line Protection flag is 'No'.