What the 600W peak pulse rating means for your protection margin
This means a 24V nominal rail can ride through a transient up to 37.5V before the diode conducts hard enough to shunt the energy — the 600W rating gives you a 16A peak current budget for a 1ms surge.
onsemi lists the P6SMB27AT3 as Obsolete. The base product number is P6SMB, and the P6SMB series includes many active 600W TVS variants in the same DO-214AA package. If your design can tolerate a different standoff voltage or clamping level, a current P6SMB part may drop in without a board change — but the 27A suffix (25.7V breakdown, 23.1V standoff) is unique to this code.
Package and mounting — DO-214AA SMB footprint
The SMB footprint is standard — the same pad layout used by the SMCJ and SMBJ families — so a board already laid out for a 600W SMB TVS accepts this part without a layout change. The 700pF capacitance at 1MHz is typical for a 600W Zener TVS — it adds about 5-10pF to the line capacitance, negligible for 1MHz signal integrity but worth noting if the protected line is a high-speed data bus.