28V rail clamp — 600W pulse rating in a DO-214AA
Its 600W peak pulse power rating (10/1000µs waveform) and 45.4V clamping voltage define the energy it can absorb without passing the overvoltage to the downstream circuit. Breakdown is guaranteed at 31.1V minimum, so the standoff voltage of 28V leaves a 3.1V margin before the diode starts conducting — enough headroom for most 24V to 28V rails without nuisance triggering.
Clamping voltage and pulse current — the transient budget
At the 13.2A peak pulse current (Ipp) the diode clamps at 45.4V maximum. That 45.4V ceiling is what the protected IC's breakdown rating must exceed — a 40V-rated MOSFET on a 28V rail would be marginal; a 60V device gives comfortable margin. The bidirectional channel handles both positive and negative transients with a single device.
Microchip lists the SMBJ28CAE3/TR13 as Active. The DO-214AA (SMB) footprint is widely stocked across multiple distributor channels.