Voltage hierarchy — standoff, breakdown, and clamping
The 1.5SMCJ6.5A: The reverse standoff voltage is 6.5 V typ — the device stays invisible to the circuit during normal operation. When a transient drives the line above 7.2 V minimum breakdown, the TVS turns on and clamps. The clamping ceiling of 11.2 V at peak pulse current is what the downstream IC sees during the event. For a 5 V rail, the 6.5 V standoff gives roughly 23 % margin above nominal; for a 12 V rail the margin is tighter, so the clamping ratio to the standoff voltage is the first thing to check against the downstream abs-max rating.
SMC/DO-214AB package and surface-mount integration
The SMC (DO-214AB) package is the industry-standard footprint for 1.5–3 kW TVS diodes on consumer and industrial boards. The cathode bar on the SMC marks the polarity — unidirectional operation only. The supplier device package field lists both SMC and DO-214AB, confirming the two naming conventions are interchangeable for this part.
General purpose transient protection — where this class fits
The 1.5SMCJ series is classified for general-purpose applications, not specifically automotive or industrial-high-reliability. Power line protection is listed as No: this part protects a signal or low-power rail, not a mains power bus.