600W bidirectional TVS for 77.8V rail protection
The P6KE91CA-B: The bidirectional configuration means a single device protects both polarities — useful on AC signal lines or DC rails where the transient can swing either way. The 77.8V reverse standoff rating is the maximum continuous DC voltage the diode can sit across without conducting — stay at or below this for normal operation.
DO-15 axial package — rework and board-fit
The bulk packaging means parts come loose in a bag, not taped and reeled — fine for bench stock or low-volume assembly, but a pick-and-place machine will need a tube or tray feeder. The DO-15 body is polarity-marked with a cathode band; for the bidirectional variant the marking is still present but the device works either way.
The 175°C TJ max is typical for silicon Zener TVS — the junction can spike during a pulse and recover without damage as long as the average power stays within the 600W peak limit. No power line protection (the part does not include a built-in filter or series element), so it is a straight shunt clamp — use it across the rail to ground, not in series with the power path.
Sourcing and lifecycle status
The base product number P6KE91 covers the whole family; the CA suffix specifies bidirectional, and the -B suffix indicates bulk packaging.