Zener TVS for 48 V rails — clamping at 77.4 V
The SMBJ48AE3/TR13 is a Microchip Technology Zener-type transient voltage suppressor designed to protect a 48 V nominal rail. Its minimum breakdown voltage of 53.3 V sits comfortably above the 48 V standoff, so the part stays transparent during normal operation and only conducts when a surge pushes the line past the avalanche threshold. Rated for 600 W peak pulse power per the 10/1000 µs waveform, it clamps at 77.4 V maximum while passing 7.7 A peak pulse current. That clamping voltage is the survival ceiling for the downstream regulator or load — if the load's absolute maximum is below 77.4 V, you need a lower-clamp TVS or a secondary protection stage.
Package and rework — DO-214AA (SMB)
The package body is marked with a cathode band; orientation is unambiguous under a loupe. Pad layout follows the standard SMB footprint, so it drops onto existing boards without a layout change.
The wide Tj window also means the part can absorb repetitive low-energy surges in a hot environment without shifting its breakdown voltage over time.