Zener TVS for general-purpose transient suppression
The P6KE91A-B is a 600 W peak-pulse-power Zener TVS diode from Diodes Incorporated, housed in a DO-204AC (DO-15) axial-lead package and supplied in bulk. The 600 W rating is tested at 25°C; derating above that follows the standard power-temperature curve for axial-lead TVS diodes.
The 125 V maximum clamping voltage at 4.8 A tells you the peak voltage seen by the downstream silicon during a surge. If the protected rail is a 77.8 V bus (the reverse standoff), the TVS stays off during normal operation and only conducts when the transient exceeds the 86.5 V minimum breakdown threshold. This gap between standoff and breakdown — about 9 V — gives a clean trigger window without nuisance triggering on ripple. The power line protection flag is set to 'No', meaning this part is not rated for continuous AC mains surge suppression — it is intended for DC rail or signal-line transient protection where the pulse is short and the standby voltage is steady.