The 1.5SMC39CA: It clamps transients at 53.9 V maximum when the peak pulse current reaches 28.2 A under the 10/1000 µs waveform. Rated for 1500 W peak pulse power, this part protects 33.3 V nominal rails from surges up to that energy level — common on 24 VDC buses with margin for the reverse standoff voltage. Breakdown occurs at a minimum of 37.1 V, ensuring the diode stays off below the rail voltage and only conducts during an overvoltage event.
The DO-214AB (SMC) footprint is shared with the supplier device package designation SMCJ — the same land pattern serves both.