Last-Buy Status and Sourcing Reality
The 1.5KE91CA-E3/51: Vishay has marked the 1.5KE91CA-/51 as Last Buy — the manufacturer's last-time-buy window is active, meaning this part is not for new designs and will not be available through the factory channel after the LTB closes. No stock-holding claim — each lot is verified for authenticity and RoHS compliance before shipment.
Protection Parametrics — What the Ratings Mean for the Board
The 12 A peak pulse current (Ipp) at the same waveform tells you the surge the diode can clamp without failing. Clamping voltage is 125 V max at Ipp — the voltage the protected rail sees during the surge. With a reverse standoff of 77.8 V, this part sits on a nominal 75 V or 80 V DC bus and holds off normal operating voltage without leakage. Breakdown voltage (minimum 86.5 V) is the threshold where the diode starts conducting — it guarantees the rail is protected before the voltage reaches the clamping level.
Bidirectional Channel and Package Fit
Single bidirectional channel — the same device clamps both polarities, so it works on AC signal lines or bipolar DC rails without needing two diodes back-to-back. Through-hole DO-201AA (DO-27) axial package — the body is 1.5KE size, suited for point-to-point wiring or PCB through-hole mounting. Bulk packaging means loose tubes or bag, not tape-and-reel.