TVS diode for 43.6V rail protection
The 1.5SMC51A: The 43.6V reverse standoff voltage means this device sits across a 36V to 42V bus without conducting in normal operation, only triggering when the line exceeds the minimum breakdown voltage of 48.5V. The 70.1V clamp ensures downstream components rated for 75V or higher see a safe voltage during a surge event.
The supplier device package is listed as DO-214AB (SMCJ), which is the standard JEDEC outline for this power level. The device does not include power line protection features — it is a general-purpose transient suppressor for signal or low-power DC buses.