It clamps transients on 12 V nominal rails — the reverse standoff voltage is 12.8 V, so it sits across the supply without conducting during normal operation. Peak pulse power is rated at 600 W for a 10/1000 µs waveform, with a clamping voltage of 21.2 V at the peak pulse current of 28 A. The single unidirectional channel handles positive-going surges; for bidirectional protection you need two devices or a different part number.
onsemi lists the P6SMB15AT3 as Obsolete. For BOM lines that still call out this exact order code, the only sourcing path is through independent distributors or the open market — we can quote against your quantity and verify date code and traceability before shipment.
Package and temperature range for the rework bench
The SMB footprint is shared with many other P6SMB-series devices, so a replacement with the same package and similar electricals can drop in without a board spin.