What the clamping spec means for the circuit
The 1.5SMCJ43A-AQ: The reverse standoff of 43 V defines the working voltage the line sits at safely — transients below this level see near-infinite impedance from the TVS. When a surge fires, the 69.4 V clamping ceiling at 21.6 A peak pulse (10/1000 µs waveform) is what the downstream bus sees — the diode absorbs 1.5 kW of that energy and clamps the overvoltage before it reaches the load. Breakdown minimum of 47.8 V keeps the TVS invisible during normal operation; it transitions from blocking to conducting within a narrow window between standoff and clamping, which matters for response latency on fast transient events.
Automotive deployment context
Junction temperature rated to 150 °C — this covers the under-hood ambient band with margin for self-heating at full pulse load; the 21.6 A peak pulse rating is sized for the ISO 7637-2 pulse severity a 12 V system can generate.
Sourcing posture — active production
The part is listed Active by Diotec Semiconductor — quoted to order against BOM quantities through independent distribution, with current pricing and lead time confirmed at RFQ.