The 1.5SMC22A-E3/57T: The footprint is standard for 1.5 kW TVS diodes — the two-pad layout with a cathode band matches industry SMC land patterns, so no custom pad geometry is needed. The 1500W peak pulse rating assumes proper thermal coupling to the PCB copper — the SMC body's large tab area conducts the pulse energy into the board's ground plane.
Clamping performance and selection fit
As a unidirectional Zener TVS, the 1.5SMC22A-/57T clamps at 30.6V maximum when the peak pulse current reaches 49A under the 10/1000 µs waveform. The reverse standoff voltage is 18.8V, meaning a 12V or 15V rail is protected without the TVS conducting during normal operation — the breakdown starts at 20.9V minimum, giving margin above the rail tolerance. The 1.5SMC series from Vishay is branded TransZorb®, a trademarked line of silicon-avalanche TVS diodes designed for repetitive surge handling. The 1500W peak pulse power at 10/1000 µs places it in the medium-power class for SMC-packaged TVS — sufficient for secondary protection on DC power inputs, signal lines, and I/O ports in industrial and telecom gear.