Transient suppression for 17.1V rails
The 1.5SMB20CA: The single bidirectional channel protects both polarities on a signal line, which is typical for telecom line-side transient protection where the pair sees both positive and negative surges relative to ground.
Peak pulse current and clamping margin
With a peak pulse current of 54.9A at the 10/1000µs test waveform, the 1.5SMB20CA can absorb a substantial surge before the clamping voltage rises above 27.7V. The 19V minimum breakdown voltage gives a 1.9V guard band above the 17.1V standoff — enough to accommodate normal ripple and DC bias without nuisance clamping. The DO-214AA (SMB) surface-mount package keeps the thermal path short to the PCB copper pad, which is critical for dissipating the 1500W pulse without exceeding the -65°C to 150°C junction temperature range.