600W bidirectional transient suppressor — obsolete but still in the channel
The P6KE91CA-T: Packaged in a through-hole DO-15 axial body (DO-204AC), it handles continuous ambient temperatures from -55°C to 175°C — suitable for industrial and automotive environments where board-level surge protection is needed on a 77.8V rail.
What the ratings mean for your BOM
The 77.8V reverse standoff (working voltage) means the diode will not conduct at normal rail voltage up to that level — it sits transparently across the line until a transient exceeds the 86.5V breakdown threshold. The 125V clamping voltage is the peak voltage the protected circuit sees under a 4.8A pulse; downstream components must survive that clamp level. Single bidirectional channel — one device protects both polarities on a single line, saving board space versus two unidirectional diodes in anti-series.
Sourcing reality — obsolete, but available
Diodes Incorporated has marked the P6KE91CA-T as Obsolete. No official successor or second-source is listed in the record. If a design-in is still open, consider pin-compatible TVS diodes in the same P6KE family with similar breakdown voltages — but no direct drop-in replacement is recorded here.